Energy Conservation In Housing, second half of book, Text Only (No Graphics copied on this web-site)

[Energy Conservation in Housing]

Second Half of:

ENERGY CONSERVATION IN HOUSING
A Collection of Data on
Energy-Efficient Housing Approaches

by: David L. Meinert

++++++++++++++++
NOTE: This Google “blog” did NOT put any of the drawings / graphics
necessary to
understand a lot of the information.
However, I have the complete (PDF) and Word documents of the text and
graphics
on this site. Go to “Home” of this site, and look at “Files” which
lists the book text in PDF format, as well as additional files on
other insulation and energy saving topics.

I also have the complete (PDF) documents of the text and graphics
on a Yahoo web-site.
The Yahoo site includes some photos of an attic and basement
insulation project. Use this link to connect to it.
http://groups.yahoo.com/group/EnergyConservationHousing
(Expect to have to sign in to the Yahoo group to access the data.)
Starting in November 2008, this data has been available on a different
site (“Multiply.com”).
http://energyconshousing.multiply.com/
The main improvement on this Multiply site is the ability to add
videos. I added some insulation videos that can be viewed on the
Multiply site. The Word and PDF documents are also on this site.
However, my home computer has been unable to open those documents on
the Multiply site due to some problem with “JavaScript.” If you run
into similar problems, the best source for the complete PDF and Word
documents is on the above Yahoo site.
Expect to have to “sign-in” to the Multiply site to access the data.
Previously the text Word and PDF documents on the Multiply.com site
were on an MSN site. http://www.msnusers.com/EnergyConservationInHousing
The MSN sites was closed in February 2009.
++++++++++++++++

The printed version was published by Vantage Press New York / Los
Angeles
in 1990 and re-printed in 1992. As of 1996, it was out of print.
This electronic version was re-edited in 2003

Contents


Introduction . . . . . . . . . . . . . . . .
vi

Acknowledgments . . . . . . . . . . . . . . .
vii
Technical conditions or problems with this electronic
version . . . viii

Part One. Energy Fundamentals: The Road to
Understanding Energy-Efficient Housing
Insulation and Energy
Efficiency . . . . . . . . . . .
1
Basic Information on Heat Loss and
Gain . . . . . . . . . 1
Vapor
Barriers . . . . . . . . . . . . . . . . .
6
Window Orientation and Energy
Efficiency . . . . . . . . 9
Radiant
Barriers . . . . . . . . . . . . . . . .
16
Infiltration of Outside
Air . . . . . . . . . . . . .
19
Development of Energy-Efficient
Homes . . . . . . . . . 22
Analysis of Energy-Efficient
Homes . . . . . . . . . . . 23

Part Two. Superinsulation: The Energy-Efficient Solution
Why
Superinsulation? . . . . . . . . . . . . . .
29
Resolving Vapor Barrier and Insulation
Problems . . . . . . 29
Heat Loss
Calculations . . . . . . . . . . . . . .
35
Shape of the Building and Heat Loss and
Gain . . . . . . . . 42
Thermal Mass and the Drop of
Temperature . . . . . . . . 43
Heating
System . . . . . . . . . . . . . . . . .
44
Cooling Tubes for Summer
Cooling? . . . . . . . . . . 48
How Much Insulation Is Actually
Needed? . . . . . . . . 51
Heating Costs for the
Year . . . . . . . . . . . . .
54
Applications of Energy Technology to New
Homes . . . . . . 58
Retrofitting Insulation in Existing
Homes . . . . . . . . 74


Part Three. House Ventilation:
Fresh Air for Tightly Constructed Homes
Evaluating Air-to-Air Heat
Exchangers . . . . . . . . . . 82
Summary of Data on Commercially Available Heat
Exchangers . . . 88
Air-to-Air Heat Exchangers: List of Selected Commercial Companies
91
Air-to-Air Heat Exchangers: Homemade
Models . . . . . . . 96

Part Four. Additional Data on Energy-Efficient Housing
Comparative Costs of
Insulation . . . . . . . . . . .
111
Assembling Superinsulated
Walls . . . . . . . . . . . 115
Vapor Permeability of
Materials . . . . . . . . . . .
116
Selecting the Appropriate Overhang for South
Windows . . . . 119
Design Temperatures for Heating and Cooling for Selected Locations
122
Percentage of Sunshine for Selected
Locations . . . . . . . 124
Ground Temperatures in Shallow
Wells . . . . . . . . . 125
Magnetic Variations from True
North . . . . . . . . . 126
Winter Solar Gain and Deviation from
South . . . . . . . 126
Solar
Position . . . . . . . . . . . . . . . .
127
Clear-day Solar Gain for Double-glazed
Windows . . . . . 128
Moisture Condensation within Sealed Panes of
Glass . . . . . 129
Other Energy-saving
Ideas . . . . . . . . . . . . .
132

References . . . . . . . . . . . . . . . . .
135
Related
References . . . . . . . . . . . . . .
138
House Construction
Information . . . . . . . . . . . 139
Manufacturers and Product
Suppliers . . . . . . . . . 140

Index . . . . . . . . . . . . . . . . . . .
145
Appendix:
Retrofitting basement
insulation . . . . . . . . . . 147
Getting started on retrofitting and existing
home . . . . . 150
Practical data on retrofitting basement floor
insulation . . . . 151
Observations on vapor barrier
effectiveness . . . . . . 152
Attic radiant
barrier . . . . . . . . . . . . .
152
Air-to-air heat exchanger – Update
information . . . . . . 153

See First half of book (pages 1-81) for Parts One and Two . . .



Part Three
HOUSE VENTILATION
Fresh Air for Tightly
Constructed Homes

Evaluating Air-to-Air Heat Exchangers

Integral to the fresh air needs of new, well-insulated homes is
ventilation to replace infiltration (which has been minimized).
Ventilation of cold outside air into the home is unpleasant if the air
is not heated in advance. When the outdoor temperatures are low, the
most economical method of getting fresh air is by use of an air-to-air
heat exchanger. This device has been also termed a Heat Recovery
Ventilator (HRV). In this text I will use the terms “air-to-air Heat
Exchangers,” or “Heat Exchangers” or Heat Recovery Ventilators (HRVs)
all to describe the same type of device.
Heat exchangers extract heat from the outgoing air and transfer it to
the incoming air. Although schematic diagrams of the exchanger make
it seem simple and inexpensive, quite the opposite is the case. As of
1989 prices, heat exchangers cost from $400 to $1,500. The price of
an exchanger is not necessarily related to heat recovery efficiency.
A heat exchanger is a relatively new product designed to fill a new
need. Many companies market various types of heat exchangers. It is
difficult to find the most suitable model with so many varieties to
chose from.

Counterflow and crossflow heat exchangers

There are two types of fixed plate heat exchangers: crossflow and
counterflow. These usually have parallel surface membranes between
which air is passed. Intake air is on one side of the plate, and
exhaust air is on the other side.



The counterflow exchanger routes the exhaust and intake air through
the exchanger in opposite directions.

By having a long course through which the air can travel, the heat is
readily exchanged between the two streams of air. A short distance of
air stream overlap usually means lower heat recovery. Some
counterflow models have very long heat exchange cores, up to 8 feet in
length, while other counterflow models have barely a 2-foot core
length. A short counterflow model can end up very efficient if it has
a lot of surface area for heat transfer. A long counterflow model
might have less surface area over a much longer distance.



The typical crossflow heat exchanger schematic diagrams show the air
streams passing at right angles to each other; significantly more than
60% efficiency cannot be expected. A single-pass crossflow exchanger
would require enormous amounts of heat-transfer area and a very slow
airflow rate to get high efficiency. Using the crossflow design,
higher heat recovery is more effectively obtained by a double-pass
crossflow core.



Double-pass crossflow models, routing the air in two passes through
the heat exchanger core before exiting, give better efficiency.
Single-pass crossflow models can be expected to get 50 to 55% heat
recovery, although some companies claim their single-pass models get
75% heat recovery. If the exchanger is made to have the air routed
through in a double-pass, the first pass recovers 53% of the heat and
the second pass through the other heat exchange element recovers 53%
of the remaining heat (0.53 x 0.47 = about 0.25). This results in
about 78% heat recovered for the two passes (0.53 + 0.25 = 0.78).
By lengthening the separation between the ports, the crossflow and
counterflow models begin to resemble each other. Indeed, there can be
combinations of the crossflow and counterflow designs.



The final efficiency of a heat exchanger is determined by a number of
factors: the arrangement of the heat exchange plates, the total
surface area available for heat exchange, and the rate of airflow. A
fast airflow rate will usually decrease efficiency. The actual
details of the internal airflow through the exchanger will help
determine the effectiveness. The heat exchange plates should be
impervious to air and moisture. There should be essentially no cross-
leakage, no mixing of intake and exhaust airflows.
Single-pass crossflow heat exchangers can be expected to have lower
efficiency than double-pass crossflow or most counterflow exchangers.
Counterflow and crossflow models can obtain better efficiency by an
increase of exchange area and by having a longer distance of air
travel within the exchanger core. Related to these fixed plate
designs are exchangers using tubes for the heat transfer surface.


Heat pipe type of heat exchangers



The heat pipe exchanger transfers heat from one stream of air to the
other by way of conductive pipes extending from the exhaust to the
intake air streams. Inside the heat pipes is some form of refrigerant
fluid, such as Freon, to transfer the heat from one side to the
other.

Rotary heat exchangers


The turning wheel picks up the heat from the outgoing stream and
transfers it to the cold stream about one-half rotation later.
Redrawn from "Heat-Recovery Ventilators," Consumer Reports (October
1985).

The rotary heat exchanger has a slowly turning heat recovery wheel
that picks up heat from one stream of air and transfers it to the
opposing stream about one-half rotation later. The rotary types range
from small home models with a 16-inch-diameter exchange wheel, to huge
industrial exchangers with up to a 13-foot-diameter exchange wheel.

The rotary exchange wheel transfers heat between the air stream as
well as transferring some moisture (and its latent heat). Recovery of
moisture, therefore, increases the overall recovery of heat. Rotary
types of heat exchangers must be engineered carefully to prevent cross-
leakage of air. As the wheel rotates from the exhaust air to the
clean air, some of the contaminated air can re-enter the building.
Most heat exchanger types recover "sensible heat" (heat that can be
sensed by touch or measured by a thermometer). "Latent heat" is the
heat of fusion or vaporization of water. If a home has air that is
too dry, using a humidifier to add moisture to the air will consume
additional heat to change the water into the vapor state. As water
vapor is recovered by an exchanger, the latent heat of vaporization is
also recovered. These types of devices have been termed Energy
Recovery Ventilators (ERVs). Not only do they recover “sensible heat”
but “latent heat” as well.
With very tightly constructed homes the objective is to remove
contaminated air and typically to remove excess moisture. Most heat
exchanger companies emphasize that their models allow no cross-leakage
of the two air streams and no moisture transfer. Rotary heat
exchanger companies and other ERV products emphasize that exchanging
moisture with the incoming air is a good feature of their product. It
is hard to know whether moisture removal or recovery is the better
feature for all applications. If the inside air tends to be too dry,
then moisture recovery is preferable. However, if the inside air is
already too humid, recovery of water vapor does more harm than good.
Heat Recover Ventilators (HRVs) are designed to recover sensible heat
and to exhaust accumulated moisture (which is most important for cold
climates). Energy Recovery Ventilators (ERVs) are designed to recover
latent heat as well, which is apparently more useful for air
conditioning in hot, humid climates.
The October 1985 issue of Consumer Reports included a review of air-
to-air heat exchangers. The Consumer Union obtained specific models
of exchangers to test for efficiency of heat recovery at two
temperatures (5° F and 45° F). Airflow capability, cross-leakage,
type of recovery unit, size, price, and overall ratings of five whole-
house units and two window models were compared. The rated
efficiencies were from 15% to 71% heat recovery. The best three units
were marginally acceptable (38% to 71%) even at their lowest airflow
rates (42 to 89 cubic feet per minute). Prices of the best three
units ranged from $540 to $1,161. The window/wall models had
approximately 50% efficiency, with an airflow capacity too low to be
effective for a superinsulated house. The performance of one
exchanger seemed extremely poor (15% to 19%). In general, Consumer
Reports recommended obtaining fresh air by using an exhaust fan or
opening windows; the cost of heating the ventilation air did not
justify use of a heat exchanger. A heat recovery ventilator was
recommended only under certain conditions: for extremely tight houses
in extremely cold climates or where unusual problems existed, such as
with radon pollution or chemical contaminants in the home.25
The problem with new, tightly constructed homes is that exhaust fans
alone cannot result in proper air quality. Since fresh air must be
introduced, the house is much more comfortable when the air is pre-
warmed. Calculations from the section "Heating Costs for the Year"
demonstrate the cost of heating fresh air with and without use of a
heat exchanger. The figures show the cost of heating ventilation air
without a heat exchanger to be about $80 per year using gas heat.
(Compare examples 3 and 4 for Duluth, Minnesota.) However, the same
size house without a heat exchanger, having a full-length basement,
and using 1.0 air changes per hour would have an annual cost for
heating ventilation air of over $300 per year. (Calculations are
based on gas heat @ $0.44 per 100 cubic foot; if only electric heat is
available, the annual costs would be over $1,000/year.) The following
factors affect the cost of heating ventilation air: the house size,
the ventilation rate, the coldness of the climate, and the cost per
BTU of heat. In the most extreme conditions, an air-to-air heat
exchanger can recover sufficient heat from exhaust air to save
hundreds of dollars per year, based on gas heating costs.

Considerable variation may exist between claimed and actual
efficiency of heat exchanger types. Different companies market
similar heat exchangers; if one company claims 75% efficiency and a
different company's comparable model claims 55% efficiency, it leads
one to doubt the claims.
Power consumption of the heat exchanger fans should also be
considered. For heat exchanger models operating continuously for 180
days per year, 65 watts power consumption will use about $20 worth of
electricity; 300 watts power consumption will use about $90 worth of
electricity (at $0.07 per kilowatt-hour).
Most companies provide accessories to improve exchanger performance.
Some models compensate for incomplete heat recovery by adding an
electric pre-heater. With such a device, the air going into the
house is heated to 100% of room temperature by electrical resistance
heat after it leaves the heat exchanger. One rotary model preheats
air going to the exchanger core to prevent core freezing when outside
temperatures are too low. Many models have a defrost cycle, and most
provide a way for condensed moisture to be removed from the exchanger.
The exchanger selected should be able to supply the fresh air needs
of the home (about 0.5 air changes per hour) on the lower speed fan
setting. As an example: a single-story 1,500 square foot house with 8
foot ceilings has 12,000 cubic feet of air, which is one air change
for this size house; half of that is 6,000 cubic feet. An exchanger
with a 100 cubic feet per minute (cfm) capacity would move 6,000 cubic
feet per hour. Larger quantities of contaminated air are removed by
switching the exchanger to the high-speed fan setting, especially
useful when combustion is taking place (cooking, smoking, or fireplace
use). Contaminated air is exhausted from the bathrooms and kitchen as
fresh air is introduced by ductwork into the other rooms of the
house. Ventilation standards from the American Society of Heating,
Refrigerating, and Air Conditioning Engineers, Inc. (ASHRAE),
recommend exhaust ventilation of 50 cfm capacity for bathrooms and 100
cfm for kitchens; this is usually supplied by manually operated
exhaust vents, used when the need arises. Continuous ventilation by
heat exchanger ducts provide less peak airflow although better
effective ventilation, since the occupants do not shut off the
ventilation system. ASHRAE further recommends a continuous fresh air
supply of 10 cfm to each room of the house.13 This is best achieved
by providing exhaust vents for the bathroom, kitchen, and laundry and
fresh air ducts for all other rooms of the house.
Most heat exchanger companies provide installation instructions for
the heat exchanger, including flow balancing. If the exhaust and
intake ductwork causes unequal resistance to airflow, the house will
be slightly de-pressurized (if outflow is greater) or pressurized (if
inflow is greater). Dampers in the ductwork must then be adjusted to
equalize the airflow. If unequal, there will be increased rates of
infiltration every time a window or door is opened, as well as driving
infiltration through any breaks in the vapor barrier.
Although there are heat exchanger models on the market that are well-
designed, efficient, and reasonably economical, it may be difficult to
find the most suitable model.
The following pages detail an exhaustive mailing research project I
did on air-to-air heat exchangers in 1988. Less than 2 years later, I
re-contacted the companies and found many had moved, changed names,
and changed products. Some had apparently completely gone out of
business, as I could find no forwarding address. (At this time in
life, it is possible to conduct an Internet search for such products,
for those companies that list their products on the “web.”)
Being a “do-it-myself” person, I felt I could do a good job designing
and making my own. In 1988, I figured how to make such a homemade
model from hardware store products.

Since late 1988 (though 2003), I have had my homemade heat exchanger
in use in my home. I have placed my “recipe” for my version in the
section of this book on homemade air-to-air heat exchangers.

Summary of Data on Commercially
Available Heat Exchangers

Comments about 1989 data: The following pages list a number of
companies marketing or manufacturing air-to-air heat exchangers.
During a 24-month period (1987-1989), I had witnessed significant
changes in the availability of products from some of the companies.
New products were added, formerly available products were deleted,
companies changed hands, and some companies went out of production.
This is not intended to be an all-inclusive list of every exchanger
type available; the listed data are subject to change over time and
with market forces.
Abbreviations: s.p. crossflow = single-pass crossflow; d.p.
crossflow = double-pass crossflow; Cross/counter = exchanger may be
rated by the company as one model or the other, although the airflow
pattern, judged by diagrams received from the company, appears to be a
combination of the two different types of flow, i.e. a short
counterflow model resembles a crossflow model and an elongated
crossflow model may be partially counterflow. Power Used = electrical
power in watts (W) or amperes (A) used by the fan motors with the fan
on the high setting. Some of the smaller exchanger models use one
motor to turn two centrifugal blower wheels for the exhaust and intake
air streams. In larger-capacity units, invariably two motors are
needed and the power consumption increases. Some of the models locate
the blower motors within the air stream, so heat given off by the
motor is added to the fresh air stream, raising the exchanger
effectiveness. The designation N/A = a value not applicable. N/A
is used to refer to cores only, which have no fans, thereby no power
consumption quantity can be assigned. Most airflow rates listed are
values with no resistance from ductwork; as ductwork is added,
resistance is added. One exchanger rated at 140 cfm reduces to 119
cfm with a moderate amount of air resistance (e.g. 0.4" static
pressure). Efficiency ratings are from company literature. Some
companies explain the efficiency at various airflow rates, outside
temperatures, and inside relative humidity; other companies state only
one efficiency rating. One heat exchanger company claims 70%
efficiency, but when tested by Consumer Reports was given an
efficiency rating of 38 to 55%. 25 The buyer should be cautious and
not necessarily accept heat recovery claims as completely accurate.

September 2003 comments: I did a search for “Heat Recovery
Ventilators” on the Internet. I also did a search of the companies I
listed from 1989. Of the 17 listed companies for 1989, there were
still several of the same names, still manufacturing Heat Recovery
Ventilators (HRVs). There may be others of these companies from 1989
that do not have a functional web-site, or have changed their name. I
found more than a dozen other HRV companies (within the first 100 web-
sites I searched), which are listed below. There were over 4,000
entries that I found on my Internet search for “Heat Recovery
Ventilators.” These Internet entries included manufacturers,
suppliers, installers, and general information on the topic.
I believe that by studying my text on this subject (and also
reviewing the data on the HRVs from 1989), you can understand the
theories of how air-to-air heat exchangers work. This can help you
understand the basic types and forms of these devices, and be better
able to know what you are looking at when investigating the products
of specific companies.
Heat Recover Ventilators (HRVs) are designed to recover sensible heat
and to exhaust accumulated moisture (which is most important for cold
climates).
Energy Recovery Ventilators (ERVs) are designed to recover latent
heat as well, which is apparently more useful for air conditioning in
hot, humid climates.


The following are HRV and ERV companies I found on my Sept 2003
Internet search.

1. Airxchange; 85 Longwater Drive; Rockland, MA 02370; Ph:
781-871-4816. Markets rotary HRVs. (See this company under my 1989
listings.)
2. American Energy Exchange, Inc.; 5737 East Cork Street; Kalamazoo,
MI, 49048; Ph: 269-383-9200. Markets large capacity HRVs (1,000 cfm to
30,000 cfm “heat wheel recovery” (rotary version), flat plate versions
(single and double-pass crossflow HRVs with aluminum cores) and heat
pipe versions.
3. American Aldes Ventilation Corporation. (See this company under my
1989 listings also.) Markets single-pass and double-pass crossflow
HRVs with aluminum cores.
4. Broan. Markets single-pass crossflow HRVs. Phone: 1-800-558-1711;
Broan-NuTone, LLC.; P.O. Box 140; Hartford, WI 53027. (See my
listings for this company under ventilation products, pg 142-144.)
5. Bryant Heat Recovery Ventilators. (No technical details of the
products were shown on the web-site.) (esshvac.com)
6. Carrier makes two different versions of ERVs for residential use.
These appear to be single-pass crossflow cores, designed for enthalpic
energy and moisture recovery. Carrier is a widely-know company with
dealers throughout the USA.
7. Chester Dawe. Markets at least one type of HRV (KMH-150 Heat
Recovery Ventilator). Many locations in Canada. One such address:
1297 Topsail Road; P.O. Box 8280; St. John's, NF; A1B 3N4; (709)
782-3104
8. Chris Smith HVAC, Inc. Markets HRVs with single-pass aluminum
crossflow cores. (cshvac.com)
9. Cleanaire. Markets single-pass crossflow HRVs. Avon Electric
Ltd.; Christchurch, New Zealand. Ph 0800 379247
10. Eco Air 56 Bay Road; Taren Point, NSW 2229; Australia. Markets
counterflow HRVs with aluminum core. Ph: 61 2 9526 2133
11. Fantech; 1712 Northgate Boulevard; Sarasota, Florida 34234;
1-800-747-1762. Markets single pass crossflow HRVs with polypropylene
core
12. Grantair Technologies; 1470, Rome Blvd.; Brossard; (Quebec) J4W
2T4; Canada. Markets residential HRVs and other products.
13. Heatilator Home Products; Hearth & Home Technologies; 1915 W.
Saunders Street; Mt. Pleasant, IA 52641; (877-427-8368). Markets
single-pass crossflow HRVs with aluminum cores and models of ERVs.
14. Honeywell makes two different versions of single-pass crossflow
HRVs with aluminum cores and crossflow ERVs. These are marketed and
installed by various companies, which can be found by Internet search
under Honeywell HRVs.
15. Kiltox Damp Free Solutions; 27 Park Row; Greenwich SE109NL; United
Kingdom. Markets HRVs.
16. Lifebreath – appears to be single-pass crossflow HRVs with
aluminum core. Indoor Air Quality Distributors; 83 Galaxy Blvd., Unit
19 ; Toronto, Ontario M9W 5X6; Canada (416) 674-7525; 1-877-839-3036
17. Newtone Home Heat Recovery Ventilators, ph 800-525-7194. Appears
to be single-pass crossflow cores with “enthalpic transfer” (moisture
absorbing/transmitting exchange plates).
18. Nu-Air Ventilation Systems; Newport, Nova Scotia; Canada, B0N
2A0; (902) 757-1910. Markets HRVs, which appear to be single-pass
crossflow cores (aluminum or plastic, depending on the model).
19. Raydot, Inc.; 145 Jackson Avenue; Cokato, MN 55321; 800/328-3813
or 320/286-2103. Markets HRVs for agricultural, industrial, and
residential uses. (See this company under my 1989 listings.)
20. RenewAire (formerly Lossnay). Markets HRVs, which appear to be
single-pass crossflow HRVs with moisture absorbing/transmitting
exchange plates. Sound Geothermal Corporation; Rt. # 3 Box 3010;
Roosevelt, UT 84066; ph 435-722-5877
21. Summeraire. Markets residential HRVs. Appears to be single-pass
crossflow design.
22. Venmar Heat Recovery Ventilators; Thermal Associates; 21 Thomson
Ave.; Glens Falls, NY 12801; 1-800-654-8263; 518-798-5500. Markets
HRVs, which appear to be single-pass crossflow, with a polypropylene
core.
23. Xetex, ph. 612-724-3101. Markets flat plate heat exchangers
typically with aluminum cores and rotary models. (See this company
under my 1989 listings.)

Summary of Data on Commercially Available Heat Exchangers (January
1989)

Company Type of Maximum % Heat Power 1989
Model no. core capacity recovery used Length Height Width Price

ACS - Hoval (Numerous aluminum crossflow cores also available in many
sizes)
PC-130-140 s.p. crossflow 140 cfm 60-75% 120 W 47" 18" 12" $920
PC-130-250 s.p. crossflow 250 cfm 60-75% 213 W 47" 18" 12" $1137
PC-230-140 d.p. crossflow 140 cfm 75-90% 120 W 67" 18" 12" $1238
PC-230-250 d.p. crossflow 250 cfm 75-90% 213 W 67" 18" 12" $1457

Air Changer Marketing: See Memphremagog listings

AirXchange
Model 570 rotary 70 cfm 75-80% 55 W 22" 13" 7.5" $438
Model 502 rotary 200 cfm 75-80% 145 W 29" 17.5" 10" $578

American Aldes
VMP H3/5 cross/counter 140 cfm 70% 1.75 A 53.5" 20" 11.5" $979
VMP H4/8 cross/counter 180 cfm 70% 1.75 A 53.5" 20" 11.5" $1015

Aston Industries (many sizes of aluminum cores are available)
Thermatube 2300
(core only) counterflow 200 cfm 70% N/A 57.5" 25" 8" $220
Aston 2000 exhaust ventilator
(blower only) N/A 1.3 A 18" 14" 12.5" $290
Aston 2412
(core only) s.p. crossflow 150 cfm 52% N/A 12" 12" 12" $290
Two Aston 2412
cores (no blower) d.p. crossflow 150 cfm 77% N/A $580

Berner Air Products
AQ Plus+ counterflow* 165 82% 370W 28" 17" 11" $820
* This is not a standard counterflow unit. see the text narrative on
Berner for details.

Cargocaire
Large industrial-sized heat exchangers available in the rotary style

Crown Industries (EZE-Breathe exchangers formerly sold by Ener-Quip,
Inc.)
RHR 100 cross/counter 100 cfm 70% 48 W 46" 8.3" 14" $682
RHR 200 cross/counter 200 cfm 70% 58 W 46" 11.3" 18" $764
RHR 400 cross/counter 400 cfm 70% 72 W 46" 14.3" 26" $999

Des Champs Laboratories
Series 175 window model 75 cfm $357
EZV-210 counter/cross 150 cfm 75% 0.8 A 46" 19" 14" $735
EZV-220 counter/cross 240 cfm 73% 1.5 A 46" 19" 14" $795
EZV-240 counter/cross 430 cfm 72% 3.0 A 49" 19" 18" $970
EZV-310 counterflow 145 cfm 85% 0.8 A 58" 19" 14" $805
EZV-320 counterflow 220 cfm 84% 1.5 A 58" 19" 14" $880
EZV-340 counterflow 415 cfm 83% 3.0 A 61" 19" 18" $1100

Enermatrix
EMX 10 s.p. crossflow 103 cfm 75% 2.11 A 28" 18" 13" $399
EMX 15 s.p. crossflow 103 cfm 75% 2.11 A 28" 18" 13" $429
EMX 20 s.p. crossflow 121 cfm 75% 2.11 A 28" 18" 13" $479
EMX 25 d.p. crossflow 250 cfm 80% 2.42 A 60" 18" 13.5" $899

Company Type of Maximum % Heat Power 1989
Model no. core capacity recovery used Length Height Width Price

Memphremagog and Air Changer Marketing
DR-150 counterflow 120 cfm 76% 84 W 60" 25" 15" $950
DR-275 counterflow 200 cfm 78% 260 W 66" 30" 15" $1130

Mountain Energy & Resources, Inc. (makes heat pipe exchangers
similar to QDT, Ltd.)
MER-150 heat pipe 160 cfm 70% 100 W 24" 24" 7" $585
MER-300 heat pipe 235 cfm 70% 180 W 26" 32" 13.5" $1085

NewAire
HE-1800c s.p. crossflow 70 cfm 73% 55 W 18" 18" 13" $420
HE-2500 s.p. crossflow 110 cfm 78% 120 W 30" 20" 12" $535
HE-5000 s.p. crossflow 210 cfm 78% 240 W 30" 20" 21" $795

QDT, Ltd.
SAE-150 heat pipe 150 cfm 70% 236 W 29" 22" 12.5" $629

Raydot
RD-225-H counterflow 225 cfm 63-82% 240 W 96" 17" 8" $846
RD-150-H counterflow 150 cfm 66-82% 150 W 96" 17" 8" $728
RD-90-H counterflow 90 cfm 71-86% 90 W 92" 9" 9" $629
RD-225-V counterflow 225 cfm 61-78% 240 W 14" 59" 14" $867
RD-150-V counterflow 150 cfm 63-79% 150 W 14" 59" 14" $752

Snappy ®; Standex Energy Systems
MA 110 s.p. crossflow 110 cfm 77% 50 W 17.5" 17.5" 7.5" $550
MA 240 s.p. crossflow 240 cfm 70% 100 W 22" 23" 8.5" $597

Star Heat Exchangers
Nova counterflow 70 cfm 65% 34 W 25" 16" 7.5" $307
Model 165 counterflow 165 cfm 80% 66 W 39" 12.5" 15" $620
Model 200 counterflow 200 cfm 80% 66 W 39" 25" 15" $770
Model 300 counterflow 300 cfm 80% 132 W 39" 25" 15" $960

Xetex
HX-50 s.p. crossflow 51 cfm 62% 74 W 11.5" 19" 7" $395
HX-150 d.p. crossflow 119 cfm 80% 80 W 18" 24" 12.5" $788
HX-200 d.p. crossflow 182 cfm 80% 120 W 25.5" 24.5" 12.7" $902
HX-250 d.p. crossflow 279 cfm 80% 125 W 18" 32" 22" $1242
HX-350 d.p. crossflow 377 cfm 80% 157 W 25.5" 40" 22" $1533

Air-to-Air Heat Exchangers:
List of Selected Commercial Companies
January 1989
ACS-Hoval, 935 Lively Boulevard, Wood Dale, IL 60191-2685, (312)
860-6800 or (800)323-5618. Markets a number of sizes of crossflow
heat exchangers. The exchangers and cores are constructed of aluminum
plates. The joints are sealed so as to prevent any cross-
contamination of the two air streams. The standard high-efficiency
models are a single-pass crossflow design rated from 60-75%. The
ultra-high-efficiency models route the air through the exchanger in a
double-pass crossflow pattern, raising the efficiency to between 75
and 90%. The standard efficiency models are rated at 140 cfm
(PC-130-140,
120 watts) and 250 cfm (PC-130-250, 213 watts). Both standard models
have total dimensions of 47" x 18" x 12" (including blowers).

(ACS-Hoval, continued): The ultra-high-efficiency models are rated at
140 cfm (PC-230-140, 120 watts) and 250 cfm (PC-230-250, 213 watts).
Both ultra models have total dimensions of 67" x 18" x 12" (including
blowers). ACS Hoval also makes heat exchange cores for other
commercial and home applications, with dozens of potential sizes
available. Their heat recouperators are made to be mounted in exhaust
ducts from ovens and furnaces to recover up to 75% of the heat from
these high-temperature exhaust gases. Prices: PC-130-140: $920;
PC-130-250: $1,137; PC-230-140: $1,238; PC-230-250: $1,457.

Air Changer Marketing, 1297 Industrial Road, Cambridge, Ontario
N3H-4T8, Canada, (519) 653-7129. Markets two different models of
counterflow heat exchangers (DR2000 series). See Memphramagog write-
up for the details.

AirXchange, Inc., 401 VFW Drive, Rockland, MA 02370, ph (617)
871-4816. Manufactures rotary type heat exchangers. Rotary-wheel
cores are available in interchangeable sensible and enthalpy
(dessicant-coated) versions. Enthalpy wheels are recommended for
cooling applications and for heating applications where retention of
some humidity is desirable. Model 570: 80% heat recovery; 22¼ " x 12
5/8" x 7½ "; 70 cfm capacity; 55 watts; 4-inch ducts; available in
wall-mounted and ceiling-mounted units. Model 502: 75% to 80% heat
recovery; 29" x 17½ " x 10"; 200 cfm capacity, 145 watts; whole house
unit for floor, ceiling, or basement installation; 7-inch ducts; a
variety of accessories such as grilles, airflow balancing grids, and
intake/exhaust fittings are also available. Depending on the
exchanger features and the accessories selected, the prices for these
exchangers are: Model 570: $438 - 623; Model 502: $578 - 917.

American Aldes Ventilation Corporation, 4539 Northgate Court,
Sarasota, FL 34234, (813) 351-3441. Markets heat exchangers of a
combined counterflow and crossflow airflow pattern; 70% heat recovery
at 90 cfm; polyvinyl chloride parallel plate core; condensate drain;
core size 38.5" long x 20" x 11.5"; 160 square foot exchange area;
blower unit is 15" x 15" x 18" with 6-inch ducts and 1.75 amps. Model
VMP H3/5: 90 cfm or 140 cfm fan setting. Model VMP H4/8: 130 or 180
cfm fan setting. Other, more sophisticated heat exchangers are
available (VMP-I). A simpler heat exchanger is available (VMP-A).
The exchanger kits include self-balancing airflow controllers that
provide constant airflow and eliminate the need to balance the airflow
for the house. The company also carries other types of heat exchanger
cores, exhaust ventilators, and numerous accessories. The listed
prices typically include most of the accessories needed for
installation. Prices: VMP H3/5: $979; VMP H4/6: $997; VMP H4/8:
$1015; VMP-A: $667; VMP-I 5/7: $1,395.

Aston Industries, Inc., P.O. Box 220, St-Leonard d'Aston, Quebec,
Canada, JOC-1M0, (819)399-2175. Markets aluminum crossflow cores and
a counterflow heat exchanger core (Thermatube 2300). The counterflow
(thermatube) heat exchanger vents the stale air through glass pipes in
the exchanger. The incoming fresh air is made to pass around the
glass pipes to pick up the heat. Capacity is up to 200 cfm, with up
to 70% heat recovery, has drain for condensate. Dimensions: 57.5"
long x 25" x 8". The Thermatube 2300 uses the Aston 2000 ventilator
module as the blower source for exhaust; 1.3 amps. It apparently does
not use a blower for the fresh air return; the return air must enter
by the negative air pressure created by the exhaust fan. The aluminum
crossflow cores (Aston 2400 series) can be obtained in 150 different
sizes from the smallest size: 12" x 12" x 4" (40 to 160 cfm) to the
largest size: 48" x 48" x 84" high (up to 24,000 cfm). The aluminum
crossflow cores can be hooked up serially to get a double-pass
arrangement, if desired. A basic crossflow core will have about 52%
heat recovery. With two cores hooked up in a double pass arrangement,
the efficiency rises to 77%. Prices: Thermatube core: $220; Aston
2000 blower: $290; Aston 2400 core: $290.


Berner Air Products Inc., P.O. Box 5410, New Castle, PA 16105, (800)
852-5015 or (412)658-3551. Berner previously marketed rotary heat
exchangers, but has switched to a counterflow model, the AQ Plus+.
Different from other counterflow exchangers, the AQ Plus+ routes
supply air through the exchanger core for a 3-second time period; it
then reverses the airflow sending exhaust air through the exchanger
core for another 3 seconds. The counterflow element is constructed of
aluminum foil with a hydroscopic coating for latent-heat (and
moisture) recovery. In addition to the counterflow heat exchanger
element, the unit employs three filters to eliminate indoor air
pollutants and allergens. The unit continuously filters (and returns)
the room air while performing the separate functions of exhausting a
portion of the room air and supplying fresh air. The unit is sold as
a "through-the-wall" installation. It has a variable speed blower,
ranging from 60 to 165 cfm; 370 watts maximum; 27.5" x 17" x 11"; 82%
heat recovery on the high setting. Price: AQ Plus+: $820.

Cargocaire Engineering Corporation, Senex Division, 216 New Boston
Street, Woburn, MA 01801, (617) 933-9010. Markets large capacity
industrial heat recovery systems of 500 cfm to 40,000 cfm; rotary
type, with rotary heat exchange element that can be 2.3 to 14 feet in
diameter; 75% heat recovery; all units too large for home use.

Crown Industries, 2101 E. Allegheny Avenue, Philadelphia, PA 19134,
(215)423-8900. This company markets three different sizes of heat
exchangers of a combined counterflow and crossflow design, having
aluminum heat exchange plates: EZE-BREATHE heat recovery ventilators
RHR 100, RHR 200, and RHR 400 (these exchangers were formerly marketed
by "Ener-quip", Inc). All have about 70% heat recovery, with two
fans, filters, condensate drain, and necessary controls. RHR 100:
100 cfm airflow; 48 watts; 46" x 8.3" x 14", with 4-inch ducts. RHR
200: 200 cfm airflow; 58 watts; 46" x 11.3" x 18", with 5.5-inch
ducts. RHR 400: 400 cfm airflow; 72 watts; 46" x 14.3" x 26", with 9-
inch ducts. Prices: RHR 100: $682; RHR 200: $764; RHR 400: $999.

Des Champs Laboratories, Inc., Box 440, 17 Farinella Drive, East
Hanover, NJ 07936, (201)884-1460. E-Z-VENT heat exchangers. Markets
more than 8 different home models of heat exchangers, counterflow (but
a relatively short core length); aluminum heat exchange elements; 2-
speed blowers; filters; condensate drains. Series 175 exchangers
are rated at 75 cfm for single-room use. Series 200 models: 3 models
ranging from 150 cfm to 430 cfm; 72 to 75% heat recovery; 24-inch
length of core; with blowers, the full dimensions are: 46" x 19" x
14" (smaller size) to 49" x 19" x 18" (larger size); large amount of
exchange area is compacted into the core (286 to 382 square feet).
Series 300 models: 3 models ranging from 145 to 415 cfm; 83% to 85%
heat recovery; 36-inch core length; with blowers, the full dimensions
are: 58" x 19" x 14" (smaller size) to 61" x 19" x 18" (larger size);
430 to 574 square feet exchange area. The company plans to market a
new model: EZ Vent II, 24" x 26" x 17", 240 cfm, $695. The company
also makes other models for commercial use of 615 to 2,200 cfm
capacity. Prices: Series 175: $357; EZV-210: $735; EZV-220: $795;
EZV-240: $970; EZV-310: $805; EZV-320: $880; EZV-340: $1,100.

Enermatrix, Inc., P.O. Box 466, Fargo, ND 58107, (701)232-3330.
Markets single-pass crossflow and double-pass crossflow heat
exchangers, polypropylene core, with filters. EMX-10: 18" x 13" x
28" (including blowers); 75% heat recovery; exhaust motor is of
greater airflow than intake (113 cfm versus 90 cfm); 2.11 amps total;
has condensate drain for both air streams; 4-inch duct size; no
defrost cycle (apparently not needed with the faster outgoing air).
EMX-15 & EMX-20 are the same size as EMX-10, but they have balanced
airflows between intake and exhaust, auto defrost control. EMX-15:
90 cfm; EMX-20: 113 cfm. EMX-25: separate blower housing (14" x 24" x
11") with 6-inch duct connections to exchanger core (35" x 18" x 13");
80% heat recovery; airflow is balanced between intake and exhaust
(about 250 cfm); 2.42 amps total; condensate drain; variable fan speed
control; dehumidistat control; auto defrost control. Prices:
EMX-10: $399; EMX-15: $429; EMX-20: $479; EMX-25: $899.

Memphramagog Heat Exchangers, P.O. Box 456, Newport, VT 05855, (802)
334-5412. Markets two different models of counterflow heat exchangers
(DR2000 series); core made from a polypropylene polymer (coroplast,
apparently); condensate drain; core size 50" long x 25" high x 15"
thick, having 280 square feet of exchange area; cold air ducts are 6-
inches in diameter; automatic defrost. To the basic core is added one
of two different warm end panels containing the blowers and controls.
The Model 150 has axial fans and 6-inch ducts; 60 cfm or 120 cfm fan
settings; 84 watts; this provides 76% heat recovery at 117 cfm and
outside temperature of 32° F; dimensions: 10" long x 25" x 15". Model
275 has centrifugal fans with 7-inch oval ducts; 120 cfm or 200 cfm
fan settings; 260 watts; this provides 78% heat recovery at 117 cfm
and outside temperature of 32°F (at -13°F, the heat recovery is 57%
for these models). Dimensions 16" long x 30" x 15"; the heat of the
motors raises the intake temperature further, giving an overall energy
performance effectiveness of 81 to 94%. The manufacturer lists that
under 2 or 3% cross-leakage can occur with these models. There is
apparently no moisture transfer with these models. Prices: Model
150 (DR-150): $950; model 275 (DR-275): $1,130.

Mountain Energy & Resources, Inc., 15800 West 6th Ave, Golden, CO
80401, (303) 279-4971. Heat pipe exchanger with lower fan power
consumption than the QDT model: MER 150: 24" x 24" x 7"; 70% heat
recovery; 100 watts total; 160 cfm at 0.25" static pressure. MER 300:
26" x 32" x 13.5"; 70% heat recovery; 180 watts total; 235 cfm at
0.25" static pressure. Prices: MER 150: $585; MER 300: $1,085.

NewAire, 7009 Raywood Road, Madison, WI 53713, (608)221-4499.
Markets three single-pass crossflow heat exchangers. HE-1800c: 18" x
18" x 13"; 70 cfm; 55 watts; 6-inch duct connections; 73% heat
recovery; filters; no condensate drain required. HE-2500: 30" x 20" x
12"; 110 cfm; 120 watts; 6-inch duct connections; 78% recovery at
110cfm; resin-coated paper core by Mitsubishi or optional polyethylene
core; filters; can order condensate hook-ups as an option. HE-5000:
30" x 20" by 21"; 210 cfm air streams; 240 watts; 8-inch duct
connections; resin-coated paper core or optional polyethylene; 78%
heat recovery at 210 cfm; condensate drain as option. Prices:
HE-1800c: $420; HE-2500: $535; HE-4000: $795.

QDT, Ltd., 1000 Singleton Boulevard, Dallas, TX 75212-5214, (214)
741-1993. Markets one model of a heat exchanger with a heat pipe type
core. SAE 150 150 cfm on high; 236 watts power consumption; 29" x
22" x 13"; 70% heat recovery; 6-inch duct connections; condensate pan
and overflow connection. Price: SAE 150: $629.

Raydot Inc., 145 Jackson Avenue, Cokato, MN 55321, (800) 328-3813 or
(612) 286-2103. Markets five heat exchangers of the counterflow
design; three are designed for horizontal installation (e.g. basement
ceiling) and two are designed for vertical installation. These
exchangers typically use aluminum heat transfer plates 0.024" thick.
The exchangers get the highest efficiency ratings (78 to 86%) at the
slowest airflow rates and the lower heat recovery ratings (61 to 71%)
at the fastest airflow rates. Blower speed is controlled using a
variable speed control switch, sold as an accessory. The typical
exchanger core has two large intake heat exchange chambers and one
exhaust chamber instead of multiple narrow chambers that can freeze in
winter. The 90 cfm model (RD-90-H) has a cylindrical exhaust chamber
and a cylindrical exterior. The company sells the basic core and
mounting straps at a specific list price; the final price will depend
on the size and type of blowers and accessories selected. Basic core
prices: RD-225-H: $498; RD-150-H: $468; RD-90-H: $385; RD-225-V: $519;
RD-150-V: $492. There are no listed prices for exchangers complete
with blowers. However, by adding the price of the basic core to the
price of two of the typical size blowers used, the following are
examples of the basic exchanger prices with blowers: RD-225-H: $846;
RD-150-H: $728; RD-90-H: $629; RD-225-V: $867; RD-150-V: $752.


Snappy ® Division, Standex Energy Systems, Box 1168, 1011 11th
Avenue S.E., Detroit Lakes, MN 56501, (800)346-4676 or (218)847-9258.
Markets two single-pass crossflow heat exchangers; May-Aire model MA
110: 110 cfm maximum capacity; 50 watts; 77% heat recovery; 17" x17" x
7.5"; 5-inch diameter ducts; condensate drain; defrost cycle. May-
Aire model MA 240: 240 cfm maximum capacity; 100 watts; 70% heat
recovery; 22" x 23" x 8.5"; 6-inch diameter ducts; condensate
drain; defrost cycle. Prices: MA 110: $550; MA 240: $597.

Star Heat Exchanger Corporation, B109 - 1772 Broadway Street, Port
Coquitlam, British Columbia, V3C-2M8, Canada, (604) 942-0525.
Markets three different sizes of counterflow heat exchangers having
interfaced tube cores and one small size of flat plate exchanger. All
models have an auto defrost cycle, axial fans with infinitely variable
speed control, and filters. The company rates the heat recovery
efficiency as the best when the outside temperature is the lowest.
Nova is the smallest model: maximum of 70 cfm; 34 watts; 65% heat
recovery; 25" x 16" x 7.5"; flat plate exchanger core; defrost cycle.
All other models have counterflow plastic tube cores. Model 165: 165
cfm; 66 watts; 80% heat recovery; 39" x 15" x 12.5"; 7-inch ducts;
defrost cycle. Model 200: 200 cfm; 66 watts; 80% heat recovery; 39" x
15" x 25"; 6- and 8-inch ducts; defrost cycle. Model 300: 300 cfm;
132 watts; 80% heat recovery; 39" x 15" x 25"; 8-inch ducts; defrost
cycle. Prices: Nova: $307; Model 165: $620; Model 200: $770; Model
300: $960.

Xetex, Inc., 3530 East 28th Street, Minneapolis, MN 55406, (612)
724-3101. Markets one single-pass crossflow and several double-pass
crossflow heat exchangers ("Heat X Changer" units). Made with
aluminum heat exchange plates. A basic crossflow model (HX-50) gets
about 62% heat recovery. Other double-pass crossflow models get 80%
heat recovery (HX-150 @ 119 cfm, HX-200, HX-250, and HX-350 @ over 350
cfm). The basic model (HX-50) is very compact (19" x 11.5" x 7") with
4-inch ducts. The double-pass models get progressively larger as the
airflow capacity increases. (HX-150 is 24" x 12.5" x 18" with 4-inch
ducts; HX-350 is 40" x 25.5" x 22" with 8-inch ducts.) On all
models the two streams of air are completely separated, with no cross-
contamination. Complete with condensate drain. Filter accessories
available. Prices: HX-50: $395; HX-150: $788; HX-200: $902; HX-250:
$1,242; HX-350: $1,533.

Notes on power consumption. The listed wattage on heat exchanger
models can be converted to the annual electrical costs in operating
the system using these formulas: Watts x hours of operation x
days operating per year ÷ 1000 = the number of kilowatt hours (KWH)
consumed per year. KWH/yr x your local electrical cost per KWH =
the total electrical cost per year.
For exchangers with only amperes listed the electrical costs can not
be as easily determined. For most electrical circuits, Watts =
Volts x Amps. However, this relationship does not hold true for
electric motors. The following quote from the book Wiring Simplified
should clarify the energy consumption relationship: "The amperage
drawn from the power line depends on the horsepower delivered by the
motor -- whether it is overloaded or under-loaded. The watts are not
in proportion to the amperes (because in motors, their 'power factor'
must be considered). As the motor is first turned on it consumes
several times its rated current, momentarily. After it comes to speed,
but is permitted to idle, delivering no load, it consumes about half
its rated current. Rated current is consumed when delivering its
rated horsepower, and more current if it is overloaded." 39
The wattage, then, can be as little as 50% of “Voltage x Amperage.”
Some heat exchanger data lists both amps and watts for the motors; in
these cases, the usual proportion is about 75% of voltage x
amperage. As an example, a reasonable estimate of power used by an
exchanger motor rated at 2.42 amps is 218 watts, as shown below.

Amps x volts x 0.75 power factor
= Approximate wattage
2.42 amps x 120 volts x 0.75 power factor = 218
watts

Air-to-Air Heat Exchangers: Homemade Models

A commercial air-to-air heat exchanger can be expensive. There are
methods to fabricate a heat exchanger with the needed materials,
mechanical skill, and time. The complete cost of materials for a
homemade whole-house heat exchanger can be half of the cost of an
equivalent commercial model. Making an air-to-air heat exchanger
requires extensive work in the time spent gathering the assorted
materials and assembly of all the parts. In addition, it may be
difficult to produce final performance comparable to some of the well-
designed commercial models. If not properly made, any retail model
will be better.

History of homemade heat exchangers

As energy costs rose, new ways were found to build homes having far
less space heating demands. Due to the nearly airtight construction
used in these new homes, indoor air tends to rapidly become stale.
Before long, techniques were being devised to provide fresh air for
energy efficient homes by recovering heat from the exhaust air.
Commercial models of air-to-air heat exchangers were not initially
available, so individuals and groups began to design heat exchangers
for residential use.
In the late 1970s, the Mechanical Engineering Department at the
University of Saskatchewan, Canada, designed a heat exchanger using
polyethylene vapor barrier as the exchange material. The polyethylene
sheeting was wrapped around plywood spacer strips to form a parallel
plate counterflow exchanger. Over the years, they designed two
different models of this exchanger. The first model used ½-inch thick
strips of pressure-treated plywood. The later model used 5/16 - inch
plywood and acoustical sealant to prevent moisture from entering the
edge of the wooden spacer strips. In the second model, each exchange
plate had a net size of 84" x 21", providing about 340 square feet of
internal surface area for the 28 exchange plates. The exchanger was
about 8 feet in overall length x 2 foot wide by 10 inches thick.
In 1985, the same group in Saskatchewan published a design (Solplan
6) of a new exchanger made from a rigid plastic sheeting material
called coroplast. Coroplast is a double-wall sheet of rigid plastic.
The air is made to flow through the spaces within the coroplast for
one air stream; air is passed on the outside of the coroplast for the
other stream of air. The homemade coroplast exchanger is a crossflow
core, with the exhaust air routed in a double pass through the
exchanger. The design is far more compact than that of the earlier
counterflow model, with the final size of the core about 36 x 36 x
12 inches.
Polyethylene sheeting as used in the original counterflow model lacks
rigidity. When the fans force air through the exchanger, the
polyethylene exchange plates tend to billow and close off the air
passageways unless the plastic is stretched very tightly during
installation. Polyethylene exchange plates tend to cause very high
internal air resistance when both blowers are operational. This
requires much electrical power to get reasonable airflow.




Coroplast is far superior to polyethylene for use as heat exchange
plates. Unfortunately, coroplast is not widely available. It is
manufactured in Canada in 4 x 8 foot sheets about ¼-inch thick. The
size makes it difficult to order coroplast by mail when not locally
available. A number of commercially available models use coroplast as
the exchange medium, having exchanger cores of single-pass and double-
pass crossflow as well as counterflow designs.

An additional homemade design for air-to-air heat exchangers
(as designed by the author of this book)
This text describes a homemade counterflow heat exchanger using
aluminum flashing as the exchange plate material. As a heat exchange
medium, aluminum is superior to plastics since it has a conductivity
hundreds of times higher, allowing good heat transfer with less
surface area. Plywood strips can be used as spacers for the aluminum
plates. Use plywood about ½-inch thick, cut in strips 1-inch wide,
cut to the proper lengths. Seal the edges of the plywood with
acoustical sealant or equivalent to prevent moisture from entering the
edges of the wood. By its nature, plywood could eventually rot from
the moisture condensing in the exchanger core even when sealant
protects the wood. Plastic lumber can be used as spacer strips (one
can find information on plastic lumber by a search of the internet).
When I designed this heat exchanger in 1988, I used a brand of plastic
garden "bender board" – which was likely one of the first types of
plastic “lumber” – I used it instead of plywood spacer strips. Bender
board was available where I lived at that time (California, in 1988),
but I never found it again after I moved to the east coast of the US.
Plastic bender board, intended to be placed in the ground as edging
for gardens, is resistant to both cold and moisture. Bender board
comes in 40-foot rolls, about 3¼-inch wide x ¼-inch thick. To provide
support and spacing for the aluminum sheets, a 1-inch width of the
bender board is sufficient. The roll can be cut into 1-inch widths
and the needed lengths with a table saw. Each roll then provides
about 120 feet of 1-inch strips. The exchanger design is a parallel
plate counterflow design about 5 feet in length, with 21 aluminum
exchange plates.

Homemade air-to-air heat exchanger core materials list:
(Materials list from 1988)
4 rolls of plastic bender board. ("Plastiform" Lawn and Garden Bender
Board, durable redwood grained plastic, manufactured by Kerber
Associates, Inc., 1260 Pioneer Street, Brea, CA 92621, (714)
871-2451) . . . . about $10 per roll. (Another brand is "Durex"
bender board, although it has a less smooth surface and an irregular
thickness, perhaps not allowing for a good air seal; manufactured by
Duraplex, Peterson Resource Company, Orange, CA 92667.) Or use an
equivalent amount of plastic lumber to have spacer strips about ½”
thick. If you can’t get ½” thick plastic lumber, you might still get
reasonable heat recovery using the more commonly available 1” thick
plastic lumber as spacer strips. Such an exchanger would use less
aluminum (due to half the number of exchange plates). (Using 1” thick
plastic lumber should make it easier to seal at the ports.)
2 rolls of 50-foot long aluminum flashing. The 14-inch width is
perhaps the minimum width that should be used. The 20-inch width will
provide 50% more exchange area for a larger-capacity airflow.
Flashing is also manufactured in 24- and 28-inch widths, although most
hardware stores may not stock the wider sizes.
5 pounds of 1 ¾ - inch (5d) galvanized box nails
½ pound of 1-inch (2d) galvanized box nails
2 tubes of silicone sealant
One box of staples ½ inch or longer and staple gun. (More nails can
alternatively be used instead of staples, although staples make it
easier to hold parts of the exchanger in position during assembly.)
Pop rivets or sheet metal screws for assembling sheet metal sections
10 feet of rigid angle metal (½ x ½-inch, to form the rigid metal
attachment flange)
1 or 2 hose or tubing connectors as condensate drains (3/8 to ½ inch
in diameter)
4' x 8' sheet of rigid insulation, ¾ to 1½-inch thick.
One large section of sheet metal (perhaps 3 foot x 10 foot in size) –
cut to specific dimensions to cover the exterior of the exchanger
(alternatively, plywood can be used).
Additional remnants of sheet metal (to make endplates and expansion
chambers)
30 feet of 1 x 1 inch sheet metal angle strip. (Alternatively, 1½ x
1½ - inch size can be used)
Sheet metal duct pipe, 6 inches in diameter. Four duct pipe sections,
at least 4 inches long each, will be needed. Two of the sections
should have a tapered end. To directly install duct booster fans in
the pipe, two of the sections should be made about 8 inches long. If
tapered ends are desired for each connector, then four original duct
pipes are needed.

Procedure. Cut the rolls of bender board into 1-inch-wide strips.
The plastic strips cut and nail similar to wood, although they are far
more flexible and difficult to handle when cutting. Make the
following lengths of the 1-inch-wide strips:

51" long strips 80 needed
8" long strips 80 needed
14" long strips 4 needed (for the outer layer on each side)
50" long strips 4 needed (for the outer layer on each side)





I tested my heat exchanger design, and found it had about 72% heat
recovery.
(The inside house / exhaust temperate is 68° F; the outside
temperature is +8° F. The incoming air is pre-heated to 51° F. Inside
to outside: 68°-8° = 60° ΔT; intake air pre-heat: 51° - 8° = 43° ΔT;
43° ÷ 60° = 71.6% recovery)


NOTE. Consider using plastic lumber, potentially cut from ½” thick
material, to serve as the spacer strips. If ½-inch thick plywood is
used instead of plastic bender board, then 40 strips of 51-inch length
and 40 strips of 8-inch length plywood will serve as spacers.
Alternatively, if the exchanger is made 3 inches shorter, 48-inch long
plywood strips with 51-inch long exchange plates could be used. The
edges of the wood must be caulked to block condensed moisture from
entering the wood in order to prevent later rotting. Wrapping the
plywood strips with 6 mil polyethylene could also prevent moisture
from entering the edges of the wood; it will still be necessary to use
sealant at the edges of the plywood strips to keep moisture from
getting around the polyethylene into the ends of the wood strips.
Pressure treated plywood might alternatively be used.

Cut the aluminum flashing into 54-inch lengths (each sheet will be 54
x 14 inches for the small size exchanger). Each aluminum roll will
make 11 plates; 21 plates will be needed for the exchanger. There is a
one-inch overlap of the aluminum plates at the port ends of the
exchanger to allow the aluminum plates to be folded together when
sealing the ports; the plates are 54 inches long and the plastiform
laminations are only 52 inches long.



Each exhaust lamination is two layers of plastiform thick; each
intake lamination is also two layers of plastiform thick. The
resultant air space is nearly ½ inch on either side of each exchange
plate.
The exchanger is assembled in sandwich fashion: an exhaust
lamination, an aluminum exchange plate, an intake lamination, an
aluminum plate, an exhaust lamination, an aluminum plate, et cetera.
It is difficult to get the first few layers started, since one is
connecting exhaust laminations to intake laminations through an
aluminum plate, not providing enough thickness for nailing until there
are at least 5 layers of plastiform strips. To get the process
started, attach an intake and exhaust layer on either side of one
aluminum plate by way of ½ inch staples. After 5 layers of
plastiform, the 2d nails can be used. Once there are 9 layers of
plastiform, the 5d nails can be used.
Using 1” thick plastic lumber should make it easier to seal at the
ports. The aluminum could be bent over and nailed to the adjacent
plastic lumber, perhaps taking less time and effort than the above-
described “rolling and flattening” of the aluminum plates. (This
process is described in the above diagram, and in more detail in the
diagram on page 102.)






Continue by alternating the laminations of exhaust and intake
plastiform. Always use an aluminum plate in between each double layer
of plastiform strips. While staples are convenient in holding the
plastiform strips in place temporarily, it will be necessary to use 5d
nails every 3 layers of plastiform strips to hold the exchanger core
together. The nails should be spaced about every 1.5 inches along the
plastiform strips to ensure a fairly good air seal, but do not use
nails through the 5" spaces reserved for the ports. Stretch the
aluminum plates and plastic strips tightly when stapling in place to
prevent bunching up the materials. Continue the assembly until there
are a total of 10 intake laminations and 10 exhaust laminations.
There are 19 exchange plates between the laminations and 2 plates on
the outside of the exchanger, for a total of 21 plates. The 19
internal plates provide the heat exchange surface. The outer plates
are secured in place by the 14-inch and 50-inch plastiform strips,
using a nailing pattern similar to the earlier layers. Be careful not
to nail through the 5-inch spaces reserved for the ports. The
thickness of the central core will be about 9 inches. There is a
possibility of some air leakage through the layers of plastiform
strips; a tight nailing pattern will minimize leakage out the sides.
Near the ends of the exchanger where plastiform strips attach at right
angles there is more possibility for leakage; the outside of the
exchanger should be caulked along these joints. As a finishing touch,
the two plastic sides of the exchanger can be covered with aluminum
flashing, requiring two more sheets of flashing, about 52 inches long
each. With the sides of the aluminum sealed under the final
plastiform strips and the ends caulked at the expansion chambers, any
air or moisture that leaks between the plastiform strips will be
trapped in that space and will not allow further leakage.
The ports are sealed by the following procedure: (1) Cut away a
section of aluminum between the ports; (2) fold the aluminum around
the plastiform strips to leave a clear opening for each port; and (3)
caulk the edges of the folded aluminum to prevent air leakage from the
opposing air stream.



The aluminum flashing material might have a coating of oil on it from
the factory. If desired, you could clean off the metal surface before
or after assembly. After I completed my basic exchanger core, I
soaked the exchanger in a large container of soapy water to dissolve
the oil and any dirt introduced during assembly. (Actually I filled a
large garbage can with soapy water, soaking the core, one end at a
time, to dissolve the oil. Then I rinsed thoroughly with a garden
hose to remove the soapy water.)






When the central core is completed, an expansion chamber is attached
to both ends of the exchanger. Two pieces of sheet metal will be
needed, 5 by 50 inches in size. These are wrapped around the port
ends of the core to make a rectangular tube, holes are drilled through
the sheet metal, and the expansion chamber is nailed to the
plastiform perimeter at each end of the exchanger. Another piece of
sheet metal (4 x 10 inches) is installed as a septum to divide the
exhaust and intake airflows. The septum is formed by making ½ inch
folds on two ends. (The final septum size is 4 x 9 inches for a 9-
inch thick exchanger core). Where the septum contacts the exchanger
between the ports the seal can be made more secure by cutting a score
line (with a hacksaw) in the plastiform and setting the septum in the
groove before sealing with caulk. All the internal joints of the
expansion chamber and septum must be caulked to prevent air leakage
and cross-leakage. Attach rigid angle metal to the perimeter edge of
the sheet metal and to the septum to allow for attachment of the end
plate at a later time. The end plate will hold the two duct pipes and
the condensate drain. Rigid insulation covers the central core; sheet
metal or plywood covers the exterior of the exchanger. For best
results, the exchanger made from 14-inch wide exchange plates should
have 6-inch-diameter ducts; 4-inch-diameter ducts will provide
sufficient airflow for only 100 cfm capacity. Careful measurements
are necessary when making the endplates, since the spacing is very
tight.
Once the exchanger is assembled, it must be hooked to the appropriate
duct connections for fresh air supply and exhaust air removal; fans
are attached to move air through the exchanger. Theoretically, if the
home is tightly constructed, when air is exhausted fresh air
automatically will be drawn in through the fresh air ductwork of the
exchanger; hooking up bathroom and kitchen exhaust fans to the
exchanger would serve this purpose. By exhausting air (without active
fresh air supply), a negative air pressure is created in the home,
potentially increasing radon infiltration as well as driving
infiltration through any break in the vapor barrier. In practice,
most exchangers have both exhaust and intake fans.



Air movement can be provided by a twin centrifugal blower (both air
streams moved by one motor) or by separate axial fans or centrifugal
blowers. The fans can be built into the warm end of the exchanger
instead of directly attaching the endplate, or a separate blower
housing can supply the air to the exchanger through ducts. Commercial
heat exchangers use either detached fan modules or built-in fans.
Either method is suitable for this exchanger, depending on the
preference of the builder. I found that the easiest method is to use
"duct boosters" in the duct connections next to the endplate. See the
listing of fan and blower suppliers after the references.
Filters should be installed to reduce dust accumulation in the
exchanger. (See page 153 for updated details on filters for this
homemade exchanger.) For up to 200 cfm airflow, 10-inch x 10-inch
filters, installed in the duct system before air reaches the exchanger
core, should provide adequate filtering.

The filter housings can be homemade from sheet metal or plywood, with
duct connections on both sides of the filter housing. There are
filter accessories from heat exchanger companies for this exact
purpose. (See product listings.) In the bathroom and kitchen provide
exhaust ducts for the exchanger. In the kitchen use a re-circulating
range hood with a grease trap instead of venting directly to the
exchanger; the exchanger duct in the kitchen removes the exhaust. The
clothes dryer should be vented directly outdoors; lint from the dryer
would quickly clog the exchanger. There are some indoor dryer vent
diverters sold for use with electric clothes dryers. These diverter
switches are used during winter to put the dryer heat (and moisture)
in the house instead of putting it outdoors. If this diverter is
covered by a nylon mesh, most of the lint can be trapped before
getting into the house air. (e.g., Cover the diverter with one "leg"
from a section of nylon hosiery to catch most of the lint that would
otherwise be expelled.) The moisture released will tend to raise the
humidity in the home excessively. If there is an effective heat
exchanger system, the moisture will be removed within a few hours.
(Author’s comment: When I tried venting dryer air inside my house, I
found an increase in mold/mildew deposits on paper products stored
near the laundry area. This occurred even with the presence of the
air-to-air heat exchanger. I believe that venting a dryer indoors it
usually a bad idea, even if an air-to-air heat exchanger is used in
the house.)
Under no circumstances should a dryer vent diverter be used with a
dryer burning fuel for its operation. (The combustion by-products
must be expelled outdoors.)
The pre-warmed fresh air should not be routed directly into the cold
air duct of the furnace. (It should be ducted no closer than 10
inches from the cold air inlet of the furnace.) If the heat exchanger
air is directly ducted into the furnace air plenum, the furnace fan
would make the airflow through the exchanger dangerously out of
balance, since the furnace fan is far more powerful than the exchanger
fans.27 The air from the heat exchanger should be distributed to all
rooms of the house for best air circulation, such as by putting ducts
through open cavities of internal walls, floors, and ceilings. If the
fresh air is brought to only one point, new air will not be obtained
in rooms away from the fresh air supply.13
The fans used to run the heat exchanger should be able to move the
needed amount of air without overworking the motor. Some axial fans
are not strong enough to move air against much resistance, whereas
most centrifugal fans are better able to maintain airflow despite
moderate resistance. For the size exchanger described in this text,
up to 150 cfm will give reasonable efficiency. An airflow rate of 150
cfm will provide 0.5 air changes per hour for a two-story home, 1,125
square feet per floor, with 8-foot ceilings. (150 cfm x 60 minutes =
9,000 cubic feet per hour. 1,125 sq ft x 8 ft ceiling x 2 floors =
18,000 cubic feet of house air. 9,000 cubic feet per hour ÷ 18,000
cubic feet per air change = 0.5 air changes per hour.) In a well-
sealed house, infiltration may supply 0.1 air changes per hour. Thus
to obtain 0.5 air changes the exchanger need supply only 0.4 air
changes per hour.
Higher flow rates are possible with this exchanger. However, the
port openings will cause significant airflow resistance. There are 10
ports for exhaust and intake, each 5 inches long and 7/16 inches
wide. This leaves only 22 square inches of open space for the air to
enter the exchanger for each direction of flow. Six-inch duct pipes
allow 28 square inches for airflow. (4-inch duct pipe provides only
12.5 square inches cross-sectional area.) Most axial fans cannot
force more than 150 cfm through a 22 square inch space, although
centrifugal blowers may have the power to nearly double the airflow
rate. Unfortunately, substantially increased electrical power is
needed to run centrifugal blowers.

Using 20-inch-wide aluminum flashing to make the exchanger, the port
openings will be 8 inches long, providing a 35-square-inch area for
the 10 laminations of exhaust and intake. This would allow nearly 250
cfm airflow rates with axial fans. Alternatively, using more
laminations of the 14-inch-wide exchanger plates will allow higher
airflow rates.





Under very cold outdoor conditions, moisture can freeze on the
exchange plates in the exhaust air stream; if sufficient ice
accumulates, the exchanger will be unable to function. Defrosting can
be accomplished by turning off the heat exchanger (requiring a very
long time for the core to thaw out) or routing air at room temperature
through the exchanger when the cold air fan is off. Solplan 6
suggests that defrosting can be done automatically by having the
intake air blower hooked to a 24-hour timer. The timer will shut off
the cold air blower on the schedule set on the timer. If the outside
temperature is above +14°F, no defrosting is needed. With outside
temperatures at 0°F, a 30-minute shutoff every 24 hours is
sufficient. At -40°F, a 30-minute shutoff every 12 hours will allow
defrosting. During the defrost mode, the warm air from the house is
still being exhausted. The heat of the exhausted air will serve to
defrost the frozen core.27 Under ordinary conditions (when the house
is closed up during cold or very hot weather), the heat exchanger
should be run continuously at the flow rate needed to provide fresh
air. (Usually 0.4 to 1.0 air changes per hour is sufficient.) Wiring
the exchanger to a humidistat is not correct, because the inside
humidity level is not necessarily an indication of the level of indoor
air pollution.
During mild weather, it may be preferable to open the windows for
ventilation, instead of using the heat exchanger. If the exchanger is
to be used to pre-cool hot, humid air in summer, there may be
condensation on the intake air passageways. For this reason, a
condensate drain can be installed on the warm air end of the exchanger
for summer use. However, I have found in 14 years of use in my house,
in hot, humid summers, that condensation is not an issue on the warm
air end of the exchanger.
The final efficiency of the exchanger will be better if the exchanger
is made thicker, using more exchange plates. Having 50% more exchange
plates will allow 50% more airflow with no loss of efficiency. It is
also possible to make single layers of plastiform (exhaust and intake
spacers) to separate the exchange plates; doing this will use 41
aluminum plates, doubling the exchange area (and doubling the cost of
the aluminum). However, with single layers of plastiform, the spacing
will be so tight that sealing the ports (by rolling the aluminum
plates) will be very difficult.

The exchanger can also be made wider (20 to 28 inches instead of 14
inches) to provide greater exchange area and airflow capacity. When
making the exchanger wider than 14 inches, it is necessary to increase
the port length to allow more airflow. (For a 20-inch exchanger
width, use 8-inch ports; for 28-inch exchanger width use 10- to 12-
inch ports.) There should be at least a 2-inch overlap of the
plastiform strips between the ports to allow adequate space for
nailing. With a port size larger than 8 inches, it may be very
difficult to fold the aluminum plates to make the port openings as
described in the diagram "Sealing the ports of the heat exchanger."
The force needed to roll that amount of aluminum is probably more than
the 3/16-inch steel rods can withstand.



In constructing the basic core of the 14-inch-wide exchanger, the
assembly time was about 30 hours and the cost of material was $220,
plus the fan costs. See the product listings for possible sources of
blowers and fans.
The ductwork of the exchanger system goes through the exterior walls
for fresh air intake and exhaust air removal. The sections of duct
pipe going through the wall should have a shield to keep out the rain
and a screen to keep out insects and birds. Position the fresh air
duct away from possible sources of contaminated air (away from car
exhaust, fireplace smoke, septic vent pipes, and the exhaust duct of
the heat exchanger).



Although 4-inch duct vents (as used for clothes dryers) going through
exterior walls can be obtained for several dollars, the 6-inch sizes
usually cost substantially more.

If the exchanger and duct connections do not cause equal airflow
resistance, flow balancing between the two air streams is necessary.
The air streams are balanced by installation of dampers in the exhaust
and intake exchanger duct pipes within the house.



Test and adjust flow balance on a calm day. Open one window and seal
it with a loose cover of polyethylene sheeting. Turn on the heat
exchanger with both dampers fully open.
If the plastic bows or curves outward, the house has positive
pressure due to excessive intake airflow. Gradually adjust the damper
on the intake airflow until the plastic sheet is limp, curving neither
in nor out. At this point the two flows are balanced.
If the plastic curves inward, the house has negative pressure,
requiring that the damper on the exhaust side be adjusted to balance
the airflow.27



The exhaust air ducts should be located high on the wall, where the
most humid and stale air is present. (Cooking and showering give off
heat and humidity, which will rise.) According to heat exchanger
manufacturers, the fresh air ducts should also be located high on the
wall to allow the cooler fresh air to mix better, instead of staying
closer to the floor. Alternatively, if you have bathroom exhaust fans
already installed, you can route the exhaust ducts into an air chamber
leading to the heat exchanger.
When the clothes dryer is in operation, it will induce some imbalance
of the airflow between exhaust and intake air of the house since it is
adding to house air exhaust and not to air intake. It is possible to
reduce this imbalance by venting outside supply air directly to the
dryer or to make a small capacity heat exchanger core specifically for
the clothes dryer. The dryer fan system will drive both airflows and
no additional fans are needed. Such a heat exchanger core must be
provided with filters and frequently cleaned to remove collected
lint. (Putting such detail into the clothes dryer exhaust system
seems to be way too much work.)

Note: I used the “Superbooster” fan set-up (shown below) when I first
installed my home heat exchanger. By the time I needed replacement
fans, that company (Ancor Industries) was apparently out of business.
I was able to find a suitable replacement in local hardware stores.
(The Tjernlund company makes such duct boosters, WITHOUT the vibration-
absorbing foam rubber feature.)








Part Four
ADDITIONAL DATA
on Energy-Efficient Housing

Comparative Costs of Insulation

When trying to get a specific level of insulation, not all methods of
insulating cost the same.
A brief survey of insulation costs from building supply stores in the
Monterey, California, area resulted in the following lowest prices
(September 1987):

R-11 fiberglass costs $19.99 for a roll 23 inches wide by 70.5 feet
long.
R-19 fiberglass costs $18.99 for a roll 23 inches wide by 39.2 feet
long.
R-30 fiberglass costs $44.80 for a roll 23 inches wide by 58.3 feet
long.
R-14.4 (2 inches thick) isocyanurate board costs $19.25 for a 4 x 8
foot sheet.
R-28.8 (4 inches thick) isocyanurate board costs $31.78 for a 4 x 8
foot sheet.
Bag of rock wool costs $5.99 to cover 24 square feet of R-19.

These prices will result in the following net cost relationships:

% cost
Cost ($) per compared
Insulation Insulation Cost ($) per of square foot to R-11
type form square foot R-value of R-1 fiberglass

fiberglass roll/batt 0.1479 R-11 0.01345 100.0%
fiberglass roll/batt 0.2527 R-19 0.01330 98.9%
fiberglass roll/batt 0.401 R-30 0.01336 99.4%
rock wool loose fill 0.2496 R-19 0.01313 97.6%
isocyanurate rigid board 0.6015 R-14.4 0.0418 310.6%
isocyanurate rigid board 0.9931 R-28.8 0.0345 256.4%

(Calculation example R-11: 23" ÷ 12 inches per foot x 70.5 ft long =
135.12 sq ft of R-11 insulation for $19.99; $19.99 ÷ 135.12 sq ft =
$0.1479/sq ft of R-11. $0.1479 ÷ 11 (R-value) = $0.01345/sq ft of
R-1.)

Fiberglass and rock wool are only 34 to 45% of the cost of
isocyanurate. Although isocyanurate is 2 to 3 times as expensive as
fiberglass, it has special advantages: compactness, rigidity, a built-
in radiant barrier, and relative moisture resistance. The
isocyanurate board can be used where sheathing is sometimes used.
Isocyanurates (R-7.2 per inch) put the same amount of insulation value
in half the space of fiberglass.

Three examples of insulating a backward double wall, made to have
about R-40 in the curtain wall, will demonstrate the comparative
differences in cost between fiberglass and isocyanurate foam.



Example one uses 4 inches of Thermax sandwiched in between the inner
and outer wall and R-11 of fiberglass between the curtain wall studs.
The final insulative value is R-39.8; with about 11 inches wall
thickness. The cost is $1.14 per square foot of insulation for the
wall (Thermax at $0.9931 per square foot of the 4-inch thickness and
R-11 fiberglass at $0.1479 per square foot).
Example two uses R-30 fiberglass between the inner and outer wall and
R-11 fiberglass between the curtain wall studs. The final insulative
value is R-41, with about 16-inch wall thickness. The insulation cost
is $0.55 per square foot (R-30 fiberglass at $0.40 per square foot and
R-11 at $0.1479 per square foot).



Example three uses rockwool or fiberglass loose fill insulation to
fill the outer wall cavity. The final insulative value is R-41, with
about 16 inches wall thickness. The cost is about $0.54 per square
foot of R-41. If the loose fill insulation is lightly packed (and
continuous with the attic insulation), settling of the insulation will
not be a problem.17

Let us assume the following house size to calculate the total cost of
insulation to fill the curtain wall: single-story, 8-foot-high
ceilings, 28 x 44 feet in size. The curtain wall height will be
about 10 feet, considering 12 inches of attic insulation above the
wall and 12 inches of floor insulation below the wall. The area of
insulation is about 1,500 square feet (10 ft x 28 ft x 2 walls = 560
sq ft. 10 ft x 44 ft x 2 walls = 880 sq ft).
Example one will cost $1,710, example two will cost $825, and example
three will cost $810 in insulation costs alone. Examples 2 and 3 will
additionally need a radiant barrier, costing about $190 for 1,500
square feet of a basic radiant barrier (double-sided foil on Kraft
paper). The extra thickness of the curtain wall will add slight
increases in framing costs for examples 2 and 3. The cost difference
between fiberglass and isocyanurate is therefore not as large as the
insulation cost alone might indicate, although it is still more
expensive overall.
Trying to mount rigid foam boards as external insulative sheathing
can be a problem if the thickness of the foam is great. It would be
difficult to nail through 4 inches of rigid foam boards, then nail
some form of siding through the foam, still being able to find the
wall studs with the nails. It can be done more easily with 2 inches
of exterior foam; this method would not allow an insulation level much
over R-33, using 2 x 6 inch framing with 2-inch exterior foam.
External insulative sheathing can potentially induce internal wall
condensation, so it is probably safer to avoid that method when using
large amounts of insulation.
Loss of insulative ability in the aging of isocyanurates is another
factor to consider. New isocyanurates may be as high as R-9 per inch,
but aged isocyanurates will eventually fall well below R-7.2 per
inch. Twenty years later, the isocyanurate foam might have an
insulation level of R-5 per inch. Four inches of isocyanurate foam
might initially give an insulative value over R-30, but could
eventually fall to R-20. Isocyanurates release freon as they age,
adding damage to the ozone layer of the atmosphere. Typically, foam
products are manufactured using such chloro- and fluorocarbons. Some
foam products give off chloro- and fluorocarbons as they age, and are
also hazardous to the ozone layer. Fiberglass and rock wool are not
only fire-retardant and less expensive, but also environmentally safer
than foam insulations. However, mineral wool insulations will not
work in all applications. For example, exterior insulation of below
grade walls is best accomplished by a water-resistant foam insulation.
There are some commercially available insulations used for
retrofitting existing walls (Tripolymer®, Air-Krete®, and Blow-In
Blanket®). These insulations require installation with special
machinery by the appropriate company. Availability is currently
limited and installation is also costly (near or over $1.00 per square
foot of wall (as of 1989), when a 3.5-inch cavity must be filled).
The need for replacing the siding or increasing wall thickness is
avoided, but the final insulative value is limited at R-13 to R-17.
Vapor barrier problems will have to be resolved, or moisture damage to
the wall can occur. The insulation will be in close contact with
existing wiring within the walls, allowing potential fire hazards.
Less cost of insulation will be incurred by retrofitting exteriorly
($0.55 per square foot for examples two and three, above, for R-40
insulation levels). Of course, there are framing costs, costs for
replacing the siding, and additional labor costs. However,
retrofitting insulation exteriorly allows installation of a continuous
vapor barrier and high levels of insulation or superinsulation.


Costs of retrofitting insulation

Retrofitting insulation for an uninsulated building in a cold climate
can provide substantial energy savings over time. The investment of
time and materials provides financial payback if the initial cost is
not prohibitively high. Expensive changes on an old house in poor
shape may never be worth the time or financial investment.
The following size house is used to estimate retrofitting costs: 28
foot x 44 foot, single-story over a crawl space. All house
specifications are as listed in example 1 for winter heat loss
calculations.

Materials Needed for Insulation Retrofitting Approximate Cost (1988)

4,500 sq ft of 6 mil polyethylene vapor barrier for wall, ceiling, and
floor $216
Acoustical sealant or other caulk to seal vapor barrier 60
76 studs for curtain wall (2 foot on center, 2" x 4" x 8 ft) 152
60 studs (2" x 4" x 8 ft) for horizontal 2x4 members,
sole plates, ledger plates, and top plate (if needed) 120
2 sheets of ¼" plywood (4 x 8 foot) for plywood gussets 16
5 sheets of ¼" plywood (4 x 8 foot) to cover the bottom of the
curtain wall 40
76 joist hangers to support the curtain wall studs 38
1,480 sq ft of R-30 fiberglass for walls (no vapor barrier needed, or
put vapor
barrier up against the continuous polyethylene vapor barrier) 592
1,480 sq ft of R-11 fiberglass for walls 220
3,720 sq ft of R-19 fiberglass for attic (three layers thick) 960
2,480 sq ft of R-11 fiberglass for crawl space (two layers R-11 + 1
layer R-19, below) 370
1,240 sq ft of R-19 fiberglass for crawl space 320
Insulation support netting for supporting crawl space insulation 35
1,500 sq ft of perforated radiant barrier for walls 190
1,700 sq ft of radiant barrier for bottom of roof rafters 210
76 furring strips (1" x 2" x 8 ft) to make radiant barrier air space
on curtain wall 65
Tyvek infiltration barrier (150 feet x 9 feet) 150
40 sheets of 3/8" plywood (4 x 8 foot sheets) to be used as
replacement siding 500
Assorted sizes of nails and lag bolts for the job 80
Continuous soffit vents and ridge vents 100
Other miscellaneous tools, wood strips, supplies, paint, and/or wood
sealer 600
150 sq ft of double-pane windows to cover existing single-pane windows
900
Air-to-air heat exchanger with needed ducts (retail model) 900
Total $6,834

With an expected materials cost nearly $7,000, retrofitting is
hardly inexpensive. If the heating bill goes from $1,000 per year to
$90 per year, the job will be paid back in 8 years if you have free
labor. If you have to hire out the job, multiply the cost by at least
three.
Retrofitting insulation in a structurally sound house can be an
economically viable means of obtaining a superinsulated house. A do-
it-yourself person could potentially retrofit an existing home over a
period of years while living in the house. Insulation upgrades could
be added, as the money becomes available instead of saving for one
major retrofit project or trying to finance the purchase of a new
superinsulated house.

Assembling Superinsulated Walls

The text and diagrams in previous sections of this book explain the
concepts of superinsulation and the techniques needed to achieve
superinsulation. During construction, it is necessary to determine
the most efficient and cost-effective method to get the house
superinsulated. The text by Nisson and Dutt explains a few methods of
assembling superinsulated walls during construction.41 Their text
shows in diagrams and in a number of photographs the step-by-step
process used to construct superinsulated walls in new construction,
using the Canadian double wall technique.
McGrath2 explained to me the sequence of assembly during new
construction and one method to get the floor vapor barrier sealed to
the wall vapor barrier.
1. The plywood floor is cut into two sections and supported beneath by
blocking. The floor vapor barrier fits between the plywood cut. The
inner wall is framed on the floor. The vapor barrier is stapled on;
sheathing is applied over the vapor barrier.
2. A duplicate outer wall is framed over the top of the inner wall.
The outer wall is spaced by the desired separation of the two walls
(3.5", 5.5", 9", or as designed). Plywood plates (¾ " thick) are
attached along the top and bottom of the wall to maintain the
separation of the two parallel walls. The insulation may be installed
in the outer wall cavities (with or without siding) at this time.
3. The double wall is tilted into place. The vapor barrier is then
sealed to the floor. The ceiling joists (or second floor joists) are
then added, the vapor barrier is sealed in place, and construction
continues to complete the exterior of the building. The inner wall
ends before the corner of the building to attach the vapor barrier to
the adjoining wall.
McGrath feels that making the inner wall structural and later adding a
curtain wall allows better vapor barrier connections (see the diagrams
on pages 68 and 71).



The three-step method illustrated above achieves a continuous vapor
barrier at the floor, although it requires extra work for the blocking
beneath the inner wall. The Canadian double wall technique uses
thinner (3/8") plywood plates, shows the vapor barrier wrapped around
the floor joist header, and has the vapor barrier covered exteriorly
by rigid insulation. Alternative methods of assembly are possible and
some of these techniques are described and evaluated in the text by
Nisson and Dutt.41

Vapor Permeability of Materials

Vapor flow through various materials is measured in perms. A low
perm rating will block the passage of water vapor, a high perm will
let vapor through readily. If a material has a perm of 1.0, it will
allow 1 grain of water to pass through a 1 square foot area in 1 hour
when there is a 1-inch of mercury vapor pressure difference between
the two sides of the material. One grain of water is about 1/7000 of a
pound.2
Since warm air holds more moisture than cold air, the warm side will
have the higher vapor pressure and water vapor will try to migrate to
the cold side. The better the vapor barrier, the less vapor that will
actually get through the wall. The moisture that does manage to get
through the vapor barrier will have to escape through the cold side of
the wall. If the outside wall also has a low perm rating, the
moisture will tend to get trapped in the wall. The outer wall should
have at least 3 times the permeability of the inner vapor barrier, or
moisture will tend to get trapped in the wall.2

Perm ratings of various materials

Sheetrock, ½” 20.0 Glidden "insulaid" paint 0.6
Exterior plywood, ¼” 0.7 Enamel paint on plaster 0.5 to 1.5
Interior plywood, ¼” 1.9 Hardboard, 1/8" 11.0 to 5.0
Glass (windowpane) 0.0 15 pound asphalt felt 1.0 to 5.6
Fiberglass insulation, 1" 116. 8" concrete block (hollow) 2.4
Aluminum foil, 0.35 mil 0.05 Concrete, 1" thick 3.2
Aluminum foil, 1 mil 0.0 Brick, 4" 0.8
Polyethylene, 4 mil 0.08 Glazed masonry tile 0.12
Polyethylene, 6 mil 0.06 Beadboard, 1" 2.0 to 5.8
Polyethylene, 10 mil 0.03 Styrofoam, 1" 1.2
Thermoply sheathing, 1/8" 0.6 Urethane board, 1" 0.4 to1.6
Tyvek ® housewrap 94. Insulation back-up paper 0.04 to 4.2
Roifoil (radiant barrier) 0.5 Foil-Ray® radiant barriers 0.02

Table derived from The Superinsulated House, by Ed McGrath.

The most widely used vapor barrier is 6 mil polyethylene (6/1000
inch thick). To make the barrier function effectively, seal the vapor
barrier at all seams and points where the membrane is crossed
(electrical boxes, wires, attic openings, and the like).

How much water vapor can get through a vapor barrier?

Even a well-sealed 6 mil polyethylene vapor barrier will have nail
holes and small tears, increasing the overall perm rating to 0.10 or
more. If the vapor barrier or its joints deteriorate with age, there
will be condensation problems in later years. TenoArm film is a 8 mil
vapor barrier material claimed to be more resistant to aging than
polyethylene. 3 (See product listings after the references.)

This formula describes water vapor transmission:
WVT = A x T x ∆P x Perms, or :
Water Vapor Transmission = Area x Time x ∆Vapor Pressure x Perms

Area = Square feet area of outside of building.
Time = Number of hours measured.
∆P = Difference of inside and outside vapor pressures.
Perms = Overall perm rating of the vapor barrier.

To demonstrate the use of the above formula, three examples will be
given using the same house dimensions: 28 feet x 44 feet x 8 feet high
(3,616 square feet outer surface area for walls, floor, and ceiling).
The vapor barrier transmission is measured for the month of January
(744 hours in the month).

Example A . This example is a house with a nearly perfect vapor
barrier, with an overall perm of 0.1. Inside relative humidity is
35%, outside relative humidity 65%, inside temperature 70°F and
outside temperature +10°F for January (northern United States).
From the table below, 70°F is 0.739, x 0.35 (RH) = 0.258.
Outside: +10°F is 0.0629, x 0.65 (RH) = 0.041. The difference
between the two values is 0.217 inches of mercury vapor pressure.
WVT = 3,616 x 744 x 0.217 x 0.1 = 58,380 grains of water, or 8.34
pounds of water. Which is about 1 gallon of water for the month of
January.

Example B. The same size house with no vapor barrier film, yet the
wallboard is covered with a vapor barrier paint, having an overall
perm of 1.0 . Since the air in the house gets dry at times, the
occupants run a humidifier intermittently to keep the RH up to 35%.
WVT = 3,616 x 744 x 0.217 x 1.0 = 583,800 grains of water, or 83.4
pounds. This is 10 gallons of water. With a 4-month heating season,
40 gallons of water can escape through the walls, floor, and
ceiling.

Example C . There is no vapor barrier, and the walls and ceilings are
painted with a flat wall paint, with a perm of 10.0 (for 2,384 square
feet). The floor makes a fair vapor barrier due to the layers of
flooring and tile, with an overall perm of 1.0 (for 1,232 square
feet). The air gets very dry, but the occupants run a humidifier most
of the time to keep the air "moist." Still the RH stays at only 15%,
since there is much continuous loss of vapor.
WVTfloor = 1,232 x 744 x 0.069 x 1.0 = 63,246 grains of water, or
9.035 pounds of water (slightly more than a gallon of water).
WVTwalls, ceilings = 2,384 x 744 x 0.069 x 10.0 = 1,223,850 grains
of water, or 174 pounds (about 21 gallons of water). With a 4-month
heating season, this could amount to over 80 gallons of water that
escapes into the wall and ceiling area. Since about half of the
surface area is ceiling, expect half of the water to get into the
attic. If the attic is not well ventilated, the moisture will
condense on the cold side of the attic (making ice balls on the nails
in the roof or freezing in the attic insulation). This ice will melt
early in spring and may run through the ceiling. If it can't drip
through, the ceiling could be seriously damaged. This same moisture
will eventually rot the structural members of walls as well as causing
peeling paint or rotted siding. A good vapor barrier is very
important to protect the walls and ceilings.

A house with a good vapor barrier will not need to add moisture in
winter. The problem will be getting rid of water vapor in the house.
Normal activities of the home (washing, showering, cooking, and
breathing) add significant amounts of water vapor to the home. An
air-to-air heat exchanger, replacing air continuously at 70 cfm from a
house with a relative humidity of 30%, will remove about 5 gallons (20
liters) of water a day under winter conditions.26
A house without a vapor barrier will tend to have dry air during the
heating season. The moisture inside is greater than outside, so the
vapor will try to get out wherever it can by going through walls,
floors, and ceilings. If the occupants run a humidifier, this will
add to the supply of moisture in the air, and even more moisture will
get into the walls and attic. If special measures are not made to
remove the moisture, over time there will be rotting of siding and
studs, with potential damage to the ceiling when the ice melts in
spring.
While a humidifier makes the occupants more comfortable in winter, it
increases vapor damage to the house. The solution is a vapor barrier,
either vapor barrier paint or some form of vapor barrier installed if
adding insulation. If insulation is added without putting in a good
vapor barrier, there can be much more rapid damage to the house.
Since the moisture will get trapped in the insulation, it will cause
rot of the wall over the years.16
The above calculations on water vapor transmission are based on
passive diffusion of vapor through walls, ceilings, floors, and vapor
barriers. In actuality, most vapor condensation is due to movement of
air through the joints of walls, floors, ceilings, through other
breaks in these surfaces, and through plumbing and electrical wiring
pathways. Due to the chimney effect, air from within the house will
rise into the attic through any available opening; this significantly
increases heat loss and eventual water vapor condensation in the
attic. Retrofitting a continuous attic vapor barrier blocks airflow
into the attic and prevents much subsequent heat loss and vapor
condensation. Retrofitting a continuous attic vapor barrier has
significant value, even though it is a laborious and time-consuming
process. Plan to do attic retrofit work during rather cool weather to
avoid hot attic temperatures.

Vapor pressures for saturated air

Degrees F. Inches mercury Degrees F. Inches mercury

-60 0.0010 +20 0.1028
-50 0.0020 +30 0.1645
-40 0.0039 +40 0.2478
-30 0.0070 +50 0.3626
-20 0.0126 +60 0.5218
-10 0.0220 +70 0.7392
0 0.0377 +80 1.0320
+10 0.0629 +90 1.4220
+100 1.9334

Table derived from The Superinsulated House, by Ed McGrath.


Selecting the Appropriate Overhang
for South Windows

South windows are useful in obtaining passive solar heating. With
south-facing windows, the proper overhang allows the winter sun to
enter but blocks the summer sun. A small overhang (18 inches) is
sufficient for most southern locations of the United States.
Progressively longer overhangs would be needed to give the same summer
shading in more northern locations.
Procedure. Use the "overhang lengths" table to design the proper
sized overhang.
1. Determine the amount of shading needed for summer, depending on the
climate. Long hot summers will need up to 6 months of complete
shading; cool summers in the north may not need complete summer
shading.
2. Determine the amount of winter exposure needed. Brief winters in
the south might not need complete window exposure; long winters in the
north may need over four months of complete window exposure.
3. Determine the best compromise between the two selections.



Examples. Miami Beach, Florida (26° north latitude), has a minimal
heating demand of 200 degree-days. Minimal solar gain is needed, but
a long shading period is advised. An overhang length of 18 to 34
inches is reasonable.
Harrisburg, Pennsylvania (40° north latitude), has cold winters
(5,251 degree-days) and hot summers. There should be good window
exposure in winter and good shading in summer. A 28-inch overhang
will provide 2 months of full exposure in winter, and two months of
complete shading in summer.





Prince George, British Columbia, Canada (54°-north latitude), has cold
winters (9,755 degree-days) and mild summers. An overhang length of
36 to 46 inches provides good solar gain in winter and reasonable
shading in summer.

Constant overhang method. Using standard framing (about 16 inches of
framing above the window) and a 5-foot window height, an overhang
length of 28 inches for all south-facing windows will provide
reasonable shading regardless of the climate. In the overhang lengths
table, a 28-inch overhang is shown to provide progressively longer
summer shading for hot southern locations (25° to 35° north latitude)
and progressively longer winter solar exposure for cold climates (45°
to 55° north latitude).
For 5-foot-high windows, the correct overhang can be determined by
use of the standard framing method, the nonstandard framing method,
the constant overhang method, or the values described in the overhang
lengths table. For other window heights, the proper overhang
dimensions can be determined by calculation.

Calculation method for overhang determination



Situation. A builder plans to use 8-foot-high windows on a south-
facing sunspace. The geographic location is 45° north latitude. The
plan is to have the windows completely exposed from 21 November to 21
January. Also, the windows are to be completely shaded from 21 May to
21 July.
Values interpolated from the Solar Position chart
Noon sun height is about 65° on 21 May and 21 July.
Noon sun height is about 25° on 21 November and 21 January.
Values from standard trigonometry tables
Tangent 65° = 2.145; Tangent 25° = 0.466



Conclusion. Overhang length = 4.75 feet Height above window =
2.25 feet


Design Temperatures for Heating
and Cooling for Selected Locations

Winter design temperatures represent outside temperatures that are
equaled or exceeded 99% of the hours in December through February.
Heating degree-days is a measure of coldness. The number of degree-
days in a calendar day is calculated as follows: subtract the average
of the high and low temperatures of the day from 65°. As an example,
if the average high for a specific day is 60° and the average low for
that day is 20°, there are 25 degree-days on that day. (60° + 20° =
80°; 80° ÷ 2 = 40°; 40° is the average temperature for that day;
65° - 40° = 25 degree-days for that day.) All of the degree-days for
a heating season are added to determine the heating degree-days for a
year. Summer design temperatures represent outside temperatures that
will be equaled or exceeded 1% of the hours in June through
September. The level of summer heat is compared to an inside
temperature of 75°. The heating degree-days and winter design
temperatures can be contrasted to the hours of summer cooling and
summer design temperatures to get a relative indication for the total
climate demands on a building. In another text, "cooling degree-days"
are quantified for selected cities in North America.41 In locations
where the heating degree-days are minimal, the cooling hours and
summer temperatures may be more significant. Below are a few
excerpts from: Insulation Manual, published by the NAHB Research
Foundation.

Winter Degree Summer Hours of
design -days design summer
State: City temp. (°F) (heating) temp. (°F) cooling

Alabama: Birmingham +17 2,710 96 1,430
Alaska: Fairbanks -51 14,500 82 190
Juneau -4 9,080 74 70
Arizona: Phoenix +31 1,680 109 2,010
Arkansas: Little Rock +15 3,170 99 1,440
California: Los Angeles +41 1,960 83 530
San Diego +42 1,500 86 620
San Francisco +35 3,040 82 180
Colorado: Denver -5 6,283 93 750
Connecticut: Hartford +3 6,170 91 630
Florida: Jacksonville +29 1,230 96 2,040
Miami Beach +44 200 91 3,250
Georgia: Atlanta +17 2,990 94 1,320
Hawaii: Honolulu +62 0 87 3,950
Idaho: Boise +3 5,830 96 680
Illinois: Cairo +4 3,820 97 1,300
Chicago -5 6,160 94 790
Indiana: Evansville +4 4,500 95 1,160
Indianapolis -2 5,630 92 870
Iowa: Des Moines -7 6,610 94 810
Kansas: Topeka 0 5,210 99 1,030
Kentucky: Lexington +3 4,760 93 1,000
Louisiana: New Orleans +29 1,400 93 2,090



Winter Degree Summer Hours of
design -days design summer
State: City temp. (°F) (heating) temp. (°F) cooling

Maine: Portland -6 7,570 87 390
Maryland: Baltimore +10 4,680 94 970
Massachusetts: Boston +6 5,630 91 660
Michigan: Detroit +3 6,290 91 710
Minnesota: Minneapolis -16 8,250 92 640
Mississippi: Jackson +21 2,260 97 1,620
Missouri: Kansas City +2 4,750 99 1,180
St. Louis +2 4,900 97 1,140
Montana: Missoula -13 8,000 92 440
Nebraska: Omaha -8 6,290 94 860
Nevada: Reno +5 6,150 95 700
New Hampshire: Manchester -8 7,100 91 610
New Jersey: Newark +10 4,900 94 840
New Mexico: Albuquerque +12 4,350 96 1,120
New York: Buffalo +2 6,960 88 610
New York +12 4,880 90 850
North Carolina: Fayetteville +17 3,080 95 1,280
North Dakota: Grand Forks -26 9,930 91 500
Ohio: Cincinnati +1 4,830 92 970
Cleveland +1 6,200 91 740
Columbus 0 5,670 92 890
Oklahoma: Oklahoma City +9 3,700 100 1,240
Oregon: Portland +17 4,700 89 340
Pennsylvania: Philadelphia +9 5,180 93 910
Pittsburgh +1 5,950 89 720
Puerto Rico: San Juan +67 0 89 4,350
Rhode Island: Providence +5 5,950 89 600
South Carolina: Columbia +20 2,520 97 1,460
South Dakota: Rapid City -11 7,370 95 660
Tennessee: Memphis +13 3,210 98 1,430
Nashville +9 3,610 97 1,210
Texas: Dallas +18 2,320 102 1,820
El Paso +20 2,680 100 1,620
Houston +27 1,410 96 2,060
San Antonio +25 1,560 99 1,980
Utah: Salt Lake City +3 5,990 97 820
Vermont: Burlington -12 8,030 88 520
Virginia: Richmond +14 3,910 95 1,090
Washington: Seattle +21 5,190 84 200
Wisconsin: Milwaukee -8 7,470 90 570
Wyoming: Sheridan -14 7,740 94 600


Percentage of Sunshine for Selected Locations

The actual solar gain a window or solar collector receives per
month is determined by several factors: 1) solar insolation (solar
heat gain per day). 2) Number of days in the month. 3) Percent actual
sunshine. 4) Deviation from true south. 5) Area of the window, less
any shading factor of the window (framing, extra panes, inside
curtains), and 6) Sky clarity factor, 1.0 (if clear) to 0.85 (hazy).
Example: Solar gain for the month of January in Kansas City, Missouri
(40° N. latitude), for a window 30 square feet in net size, facing 30°
from true south can be calculated:
1415 BTU/square foot/day x 31 days x 0.55 clear days x 0.90 deviation
x 30 sq ft
This gives about 651,400 BTUs solar gain for the month of January.

Location Mean percent Sunshine Location Mean percent Sunshine
Winter Summer Winter Summer

Alabama: Birmingham 45 65 North Carolina: Asheville 50 60
Alaska: Fairbanks 37 44 Raleigh 53 63
Juneau 27 31 North Dakota: Bismarck 53 68
Arizona: Phoenix 79 87 Ohio: Cincinnati 42 70
Arkansas: Little Rock 48 72 Cleveland 30 69
California: Eureka 41 51 Oklahoma: Oklahoma City 58 77
Fresno 52 96 Oregon: Portland 28 63
Los Angeles 70 76 Roseburg 25 72
San Francisco 55 68 Pennsylvania: Harrisburg 46 65
Colorado: Denver 66 68 Philadelphia 50 62
Connecticut: Hartford 48 61 Pittsburgh 34 62
Florida: Jacksonville 57 63 South Carolina: Charleston 58 67
Miami Beach 68 65 Columbia 54 65
Georgia: Atlanta 49 64 South Dakota: Rapid City 58 71
Idaho: Boise 42 83 Tennessee: Knoxville 44 63
Illinois: Chicago 45 71 Memphis 47 74
Indiana: Indianapolis 42 71 Nashville 44 69
Iowa: Des Moines 53 70 Texas: Austin 48 76
Kentucky: Louisville 42 70 Brownsville 46 76
Louisiana: New Orleans 48 61 El Paso 75 81
Massachusetts: Boston 50 63 San Antonio 49 73
Michigan: Detroit 35 67 Utah: Salt Lake City 50 81
Minnesota: Duluth 47 64 Vermont: Burlington 34 60
Minneapolis 48 68 Virginia: Norfolk 53 66
Mississippi: Vicksburg 47 71 Richmond 51 64
Missouri: Kansas City 55 73 Washington: Seattle 28 55
St. Louis 47 71 Spokane 30 76
Montana: Helena 48 71 West Virginia: Elkins 34 55
Nevada: Las Vegas 76 87 Parkersburg 32 61
New Hampshire: Concord 48 57 Wisconsin: Green Bay 45 66
New Jersey: Atlantic City 53 66 Madison 44 67
New Mexico: Albuquerque 71 78 Milwaukee 44 68
New York: Albany 44 62 Wyoming: Cheyenne 65 69
New York City 52 65 Sheridan 56 72

This table is derived from: Designing & Building a Solar House, by
Donald Watson. The sunshine values
are averaged for three months of winter and summer: winter –
December, January, and February, and
summer – June, July, and August).

Groundwater Temperatures in Shallow Wells

Groundwater is available in most parts of the United States. The
temperature of groundwater remains moderate and relatively stable year-
round. Groundwater could be used as a source of heating and cooling
for heat pumps.
A number of states regulate the withdrawal, use, and discharge of
ground water. Local authorities should be consulted to determine the
current regional regulations. Also, the case can be made that to use
groundwater solely as a heat exchange medium is ecologically wasteful.
It is not necessary that water utilized in a heat pump be used once
and discharged. Water can be re-circulated between a sealed storage
well and the heat pump. When the water is in the well, its
temperature is allowed to equilibrate with the surrounding water and
earth. In this way, heat is extracted from or deposited in the ground
without using up valuable water.
The figure below demonstrates the mean temperatures (°F) of
groundwater in shallow wells (30 to 60 feet deep) in the United
States. 38

Groundwater temperatures in shallow wells


A text by McConnel shows similar temperature data, listing in table
format the expected "Ground Temperatures below the Frost Line." 30
The values listed by McConnel, show a similar temperature distribution
throughout the country. The temperature values in the above map
indicate potential thermal demands on sections of buildings below the
frost line. As well as providing an indication of the feasibility of
using a geo-thermal heat pump, these temperature values can also
indicate the thermal effectiveness of "earth-tubes."

Magnetic Variations from True North

A magnetic compass helps find the approximate direction, but true
north does not coincide with magnetic north throughout the country.
Solar orientation should be corrected to the true south direction to
obtain the best solar gain. Due to the molten nature of the earth's
metallic core, the magnetic poles continue to shift somewhat each
year.



Alternative methods: 1) North can be determined by the position of the
North Star, accurate within a few degrees. 2) Solar noon is midway
between sunrise and sunset. Local newspapers may list the time of
sunrise, sunset, or solar noon; the shadows cast at solar noon will
help determine true south. 3) Daytime shadows: a) Drive a 5-foot
stake vertically in the ground and mark the end of the stake's shadow
at one time during the morning. b) Using a string tied to the base of
the stake and to a pointed stick, draw an arc through the end of the
shadow to the other side of the stake. c) Mark where the end of the
afternoon shadow intersects the arc. d) Connect the ends of the
shadows with a line. e) Bisect the line; this midway point is
directly north of the stake casting the shadow.

Winter Solar Gain and Deviation from South



Solar Position
The table below lists the sun height (altitude in southern sky) at
noon on the 21st of the month for major latitudes. Also shown is the
sun's azimuth at sunrise and sunset; this is the number of degrees
away from south, where 90° is directly east or west.

(Above table derived from Designing & Building a Solar House, by
Donald Watson)
The solar position at noon can be interpolated for latitudes not
listed on the above chart. The approximate position of the sun
compared to the equator of the earth is shown on the chart below. The
listed values are for the 21st of each month.


In the Southern Hemisphere, the opposite window orientation is needed,
meaning face windows NORTH to maximize winter solar gain. Another way
of putting it: “Face windows toward the equator to maximize winter
solar gain.” (And at the equator there’s no winter to worry about.)

Clear-day Solar Heat Gain for Double - glazed Windows (BTU/sq ft/
day)









Values listed account for 26% reflection/absorption from double-
glazing. Solar gain tables are
derived from The Passive Solar Energy Book and Solar Energy:
Fundamentals in Building Design.

Moisture Condensation
within Sealed Panes of Glass

Double-glazed windows usually are manufactured with two panes of
glass sealed in a frame separated by an insulating air space. There
is no ventilation between the panes of glass. However, the
manufacturer usually installs desiccant crystals in the spacer bars
holding the panes of glass apart. The desiccant will absorb moisture
that gets around the inside pane. Under high inside humidity
conditions, especially if the inside pane develops a poor seal,
condensation eventually may occur between the panes. Usually these
windows must then be replaced. However, with some windows this
problem can be resolved by venting the space between the panes to the
outdoors. A hole must be drilled into the approximately 3/8-inch
space between the panes and then intersect this hole by drilling
another hole from the outside. Careful measurements must be made in
advance to avoid striking the glass panes. Only a small drill hole is
needed. Small ventilation passageways allow the condensed moisture
eventually to escape to the outside. Typically the spacer bars
separating the panes have desiccant crystals. If such crystals are
released between the panes, it could cause a bigger mess. First drill
the hole into the frame, to reach the space between the panes. Then
it should be possible to insert a “tension pin” (the same size as the
drill bit – tension pins are sold by some hardware stores) into that
opening to block the crystals from getting between the panes. (Leave
the tension pin in position to keep crystals from falling between the
panes; see the diagram on the next page for how to position the vent
holes.) Continue with the second hole to vent the space between the
panes to the outside. If you are unsuccessful, you may still have to
replace the window.
Related comments. Some energy consultants in the southern United
States recommend that a vapor barrier be placed both on the interior
and exterior of walls in hot, humid climates. However, observing the
above-mentioned vented windows in cold winters and long hot, humid
summers (near Savannah, Georgia), the condensation did not return even
in summer. This suggests that such "double vapor barriers" for walls
may also be unnecessary in some hot, humid climates.









Other Energy-Saving Ideas

Water-saving showerheads

There are many water-saving showerheads on the market that claim to
use small amounts of water. The objective is to get a conservative
flow rate without lessening the quality of the shower. A good feature
is a small shutoff valve in the showerhead that stops the water flow
while you lather with soap. The shutoff valve should actually keep
the water flowing at a slow rate to reduce mixing of the hot and cold
water within the pipes. A well-designed water-saving showerhead will
reduce hot water utility costs, since there is a significantly
decreased water flow rate during the course of the shower. One model,
(SaverShower, model SS-2, by Whedon Products, Inc., 20 Hurlbut Street,
West Hartford, CT 06110) has water-saving features with a durable
brass construction. Up to $200 savings a year on fuel and water costs
is claimed for an average-sized family using this showerhead compared
to a conventional shower head. This product received high ratings as
an aerating low-flow shower head when evaluated by Consumer Reports in
June 1985. SaverShower is sold by True Value and Ace Hardware stores
(as of 1989). Numerous other brands of water-saving shower heads are
available at hardware stores and some department stores.

Reducing water heating costs

An energy-efficient house can have a higher water-heating bill than
the space heating bill. Use of conservation techniques can reduce the
water-heating bill.

1. Use brief showers instead of baths.
2. Fix leaky faucets. A dripping hot water faucet not only wastes
cold water but heated water as well. Water costs can really add up
over time; one drop every two seconds will waste over 170 gallons per
year.
3. Use cold water for laundry whenever possible.
4. Add insulation to the hot water tank and to the water lines leading
out of the tank and for about three feet before coming into the tank.
However, insulating a water heater can cause problems. With gas water
heaters, the insulation should not cover the combustion chamber of the
tank and should avoid the exhaust flue, (unless the insulation is
resistant to combustion). For electric water heaters, do not insulate
the part of the tank near the heating elements. The excess heat
trapped can melt the electrical insulation and burn out the heating
element. Some new models of water heaters are improved so as not to
require added insulation except for use on the pipes.
5. Insulate hot water lines en route to points of usage. In new
construction, try to keep a short distance from the hot water tank to
the points of usage.
6. Set the water heater temperature no higher than 120° F. 24


Two-tank system. Water entering a home can be significantly colder
than temperatures inside the house. In some climates, water enters
the house at 45° F. Water can be preheated before reaching the hot
water tank by use of an uninsulated water storage tank put in the
water line before the water heater. If the room temperature is 70°,
part of the water heating can be taken care of by house heat as the
water has time to reach room temperature. Although this method takes
heat from the house, an energy efficient house has excess heat for
eight or more months a year. The water is then preheated from 45° to
70° (about 25°), leaving an additional 50° to be heated by the water
heater.24
If a sunspace is used, excess heat from the sunspace can be vented to
the house to help with the space heating needs. Alternatively, excess
heat from the sunspace could be first vented into a chamber containing
small sealed water bottles for thermal storage. If the two-tank
method of water heating is used, the pre-heating tank could be
positioned to receive heat from the sunspace, to further pre-heat the
water before reaching the water heater. This might pre-heat the water
to perhaps 85° F.
Solar panel designs. Solar hot water heaters are available for
domestic use. Some do-it-yourself plans are available for solar water
heaters. There is higher cost and complexity to solar systems as well
as limitations, since solar heat is not always sufficient for the
demand. Furthermore, protection from freezing must be designed into
such systems for many geographic locations. One heat pipe type solar
water heater reportedly eliminates any freezing problems. 34
Another possibility for solar water preheating is the Sunflare 2000.
The solar water pre-heater has a built-in reflector that focuses
sunlight on the black surface of the water tank. This device is
intended for outdoor use in moderate and tropical climates. It could
be suitable year-round in colder climates if used in a sunspace
providing direct solar exposure of the unit (Practical Homeowner,
December 1987, p. 67).

Water-saving toilets

Most conventional toilets (as of the late 1980s) used 3.5 gallons of
water per flush and were termed water-saving toilets because they use
less than the older 5+ gallon toilets.
Newer water-saving toilets use typically 1.6 gallons per flush.
Toilets using 1.6 gallons work essentially the same as conventional
toilets. However, they are engineered to require less water to
complete a thorough flushing of the bowl. These toilets supply the
proper amount of water to initiate the siphon action that begins the
flush, water to rinse the bowl, and just enough water to refill the
bowl to its proper position. The 1.6-gallon water-saving toilets will
often clear the bowl more effectively than some 3.5-gallon toilets.
The new water-saving toilets are better designed to flush down the
drain, whereas some conventional toilets waste much water swirling
around the bowl. Even when an additional flush might be needed, the
new water-saving toilets refill quickly since there is much less water
to replace. It might appear that such a small volume of water cannot
move the waste material adequately through the sewer lines even if it
removes it from the bowl. However, the additional water running
through the same sewer lines for hand washing and bathing will serve
to move the waste material through the sewer pipes.
There are many versions of ultra low-flush toilets; a few brands are:
Superinse, Ultra-One/G, Cashsaver MX, Microflush, and Cascade.
Superinse and Ultra-One/G look and work similar to earlier made 3.5
gallon toilets, except for their low water usage.

The Ifö Cascade, a Scandinavian design, is slightly different from
conventional toilets in that the flush lever is on the top of the
tank. (Since the top of the tank has the flush lever and is dome-
shaped, it cannot be used as a shelf for assorted bathroom supplies.)
The Cashsaver MX, also marketed as Flushmate, has a flat top to the
tank, with the flush button in the center of the tank top. The
Cashsaver MX uses an air-tight chamber within the tank. The high-
pressure water from the supply line forces water into the chamber.
When flushed, the high-pressure water accomplishes the flush. The
compression tank apparently can be retrofitted into some existing
toilets. The company claims the most effective cleansing of the bowl
and the best drainline carry of any toilet on the market.
The low-volume Microflush has a flapper valve in the toilet that
opens during the flush. The waste material moves through the opening,
the flapper valve closes, and a compressed air system forces the waste
material through the sewer pipes.35

Water-saving toilets

Allegro (1.6 gal.): Mansfield Plumbing Products, 150 First St.,
Perrysville, OH 44864
Aqualine (1.5 gal.): U.S. Brass, Bobby Rogers, 901 10th St., P.O.
Box 37, Plano, TX 75074
Atlas (1.5 gal.): Universal Rundle, 303 North St., Newcastle, PA
16103
CraneMiser (1.6 gal.): Crane Plumbing, 1235 Hartrey St., Evanston,
IL 60202
Cashsaver MX (1.4 gal.): Water Control International, Inc.,
2820-224 West Maple Road, Troy, MI 48084
Flush-o-matic (0.25 gal. -- mechanical trap seal): Sanitation
Equipment, 35 Citron Court, Concord, Ontario, Canada L4K257
Hydro Miser (1.6 gal.): Peerless Pottery, P.O. Box 5581,
Evansville, IN 47716
Ifö Cascade (1.0 to 1.5 gal.): Ifö Water Management Products, 2882
Love Creek Road, Avery, CA 95224
Madera Aquameter (1.6 gal.): American Standard, P.O. Box 6820,
Piscataway, NJ 08855-6820
Microflush or Toto (Microflush: 0.5 gal -- an air compressor and air
storage tank are also needed; or Toto: a 1.6 gal. gravity-fed flush):
Microphor, Inc., 452 East Hill Road, P.O. Box 1460, Willits, CA
95490
Pearl (1 cup water -- mechanical chemical foam flush): Water
Conservation Systems, Damonmill Square, Concord, MA 01742
Santa Fe (1.6 gal, adjusts to 1.9 gal.): Artesian Plumbing Products,
201 E. 5th St., Mansfield, OH 44901
Superinse (1.1 gal.): Thetford Systems, Inc., Ann Arbor, MI 48106
Turboflush (1.6 gal.): Briggs, 4350 W. Cypress St., Suite 800, Tampa,
FL 33607
Ultra Flush (1.6 gal.): Gerber Plumbing Fixtures Corp., 4656 W. Touhy
Ave., Chicago, IL 60646
Ultra-One/G (1.4 gal.): Eljer, Three Gateway Center, Pittsburgh, PA
15222
Veneto (1.5 gal.): Parcher, Inc. 13-160 Merchandise Mart, Chicago,
IL 60654
Wellworth Lite (1.5 gal.): Kohler Company, Kohler, WI 53044

Many of the above addresses were extracted from: Kourik, Robert,
Toilets: The Low-Flush/No-Flush Story, Jan/Feb 1990, Garbage
magazine, P.O. Box 56519, Boulder, CO 80322-6519.

I have heard of consumers unhappy with the requirement to have low-
flush toilets in new construction. Changes in Federal Law mandated
the use of low-flush toilets. However, the law did not mandate good
performance in low-flush toilets. Before installing such a toilet, it
can be a good idea to consult a reference source, such as Consumer
Reports magazine, to determine a suitable brand.

Additional Commentary on Toilets. In 1988 I moved into a newly built
house, which had 3.5-gallon toilets installed. Having just researched
various types of ultra low-flush toilets, I was disappointed in having
the 3.5 gallon versions. I eventually replaced all three of these
toilets with ultra low-flush (1.6-gallon) versions, for various
reasons. I selected a brand based on performance cited in Consumer
Reports magazine (Eljer Patriot). Over time, I found that indeed
there are conditions where the low-flush toilets do sometimes “back-
up” more easily during flushes. However, the consequences are not as
severe. With the older 5+ gallons per flush toilets, if they didn’t
flush down the drain on the first flush, they overflowed onto the
floor. With the 3.5-gallon toilets, sometimes it didn’t flush fully
on the first flush. If it was actually backed-up, and then you
flushed it again, it would typically overflow onto the floor. With
the ultra low-flush versions, with two flushes on a backed up toilet,
it does not usually overflow. Then you realize you need a plunger,
but that “cleanup” is relatively easy.
In 2005, I moved again, just several miles away to another house,
having 3 toilets of the 3.5-gallon versions. In 2007, I replaced all
three toilets with the Eljer Titan version. This brand and version
appears to be the most efficient performance that can ever be hoped
for, and was top rated at this time by Consumer Reports. The list
value for the toilet was about $400, but was carried in the basic
white color by the local Lowe’s store, for about $260 total for the
base + tank assemblies. This version has an elongate bowl, higher
toilet (seat) height (16.5” instead of the usual 14”), which makes it
a much more comfortable seat to use, especially for tall people. Not
only that, but the toilet seems unable to be clogged or to overflow.
It still uses 1.6 gallons per flush, yet it has a more powerful
flush. In over a year of use, none of the 3 toilets have once showed
any sign of back up or failure to flush.

References

1. Wolfe, Ralph, and Peter Clegg. Home Energy for the Eighties.
1979. 264 pages. Garden Way Publishing, Pownal, Vermont 05261. The
copyright for this text is held by Ralph Wolfe and Peter Clegg. This
text is out of print, as of 1990.
2. McGrath, Ed. The Superinsulated House. 1981. 103 pages. That
New Publishing Company, 1525 Eielson Street, Fairbanks, Alaska
99701. The price was $11.95 in April 1987. As of 1988 this book was
out of print. The Superinsulated House contains a wealth of data on
how to build energy-efficient homes in the coldest of climates.
3. Flower, Robert G. "1987's Greatest Hits," December 1987, Practical
Homeowner Magazine, pages 18-22 give data on energy-saving
products. Copies of Practical Homeowner cited in this and other
references may be requested from Practical Homeowner, 27 Unquowa Road,
Fairfield, CT 06430, (203) 259-9877.
4. Flower, Robert G. "The Super-Cool House," August 1987, Practical
Homeowner Magazine, pp. 66 - 69.
5. Flower, Robert G. "The Tighter Wall," October 1987, Practical
Homeowner Magazine, pp. 90 - 94.
6. New House Planning & Idea Book. 1983. 91 pages. Alberta
Agriculture, Home and Community Design Branch, Edmonton, Alberta
(Canada). United States edition published by: Brick House Publishing
Co, Inc., P.O. Box 134, Acton, MA 01720.
7. Langdon, William K. Movable Insulation. 1980. 379 pages.
Rodale Press, Inc., 33 E. Minor Street, Emmaus, PA 18049. This
book contains much data on insulating windows by various types of
shutters, shades, and quilts.
8. The Miracle of Rigid Vinyl. This informational brochure was
prepared by LEA Products Inc., Manufacturers of Vinyl Windows, 2642
Roselle Street, Jacksonville, FL 32204. Data in this brochure were
derived from Heating, Ventilation and Air Conditioning Guide,
American Society of Testing Materials, ASTMC-177.


References (continued)

9. Flower, Robert G. "Smarter Windows," June 1987, Practical
Homeowner Magazine, pages 68-69. Additional comments on Aerugel
are presented in the June 1989 issue of Practical Homeowner , page 8.
10. Reflective radiant barrier tests conducted by the Research and
Development Division of the Florida Energy Center at Cape Canaveral.
Data printed in a 4-page brochure from Roy & Sons, Inc. may be
requested from Roy & Sons, Inc., P.O. Box 2223, Irwindale, CA
91706, manufacturers of residential radiant barriers.
11. "R-FAX Insul-Foil, Insulation Applications," information card,
1986. 2 pages. Data may be requested from R-FAX Technology,
Manufacturer of Foil Insulation, 661 East Monterey Avenue, Pomona, CA
91767, (714) 662-0662 or (800) 662-0663.
12. "Radon Detectors," July 1987, Consumer Reports magazine, pages
440 to 446. Consumer Reports, P.O. Box 2480, Boulder, Colo 80322.
13. Heat Recovery Ventilation for Housing: Air-To-Air Heat
Exchangers. 1984. 31 pages. Prepared by the National Center for
Appropriate Technology, P.O. Box 3838, Butte, Montana 59702-3838.
For sale by the Superintendent of Documents, U.S. Government Printing
Office, Washington, D.C. 20402, phone (202) 783-3288. Cost: $2.25
as of August 1987. Ask for report number 061-000-00631-1. This text
thoroughly explains pertinent concepts about air-to-air heat
exchangers.
14. Brochure on Tyvek® Housewrap from Dupont. Similar data was
presented on a single-page form (E-45684-2) from Dupont; it was
distributed as sales information and printed on Tyvek ®.
15. "Energy-Saving Housewraps." September 1987, Practical Homeowner
magazine, page 84.
16. Home Improvements Manual. 1982. 384 pages. Pages 352 to 379
deal with energy saving renovations. Copies can be requested from The
Readers Digest Association, Inc., Pleasantville, New York.
17. Metz, Donald. Superhouse. 1981. 150 pages. Garden Way
Publishing, Pownal, Vermont 05261.
18. Shurcliff, William A. Super Insulated and Double Envelope
Houses. 1981. 182 pages. Brick House Publishing Company, P.O. Box
134, Acton, MA 01720.
19. Marshall, Brian, and Robert Argue. The Super Insulated Retrofit
Book; A Homeowner's Guide to Energy Efficient Renovation. © 1981,
208 pages. Renewable Energy in Canada, 107 Amelia Street, Toronto,
Canada M4X 1E5,
20. Coffee, Frank The Self Sufficient House. 1981. 213 pages.
Holt, Rinehart & Winston, 383 Madison Avenue, New York, NY 10017.
21. "An Energy Miser," from Home Plan Ideas, Spring 1985, Better
Homes and Gardens Building Ideas. Pages 24 to 29. Published by:
Special Interest Publications, Publishing Group of Meredith
Corporation, 1716 Locust Street, Des Moines, Iowa 50336.
22. McGuigan, Dermot, and Amanda McGuigan. Heat Pumps. 1981. 202
pages. Garden Way Publishing, Pownal, Vermont 05261.
23. Eklund, Ken, and David Baylon. Design Tools for Energy Efficient
Homes, 3rd edition. 1984. 126 pages. Ecotope, Inc. 2812 East
Madison, Seattle, WA 98112, (206) 322-3753. Ecotope also provides
advisory services to builders on how to meet current building energy
codes.

References (continued)

24. Energy Efficient Housing: A Prairie Approach. 1980 and 1981. 31
pages. Energy Research Development Group, Department of Mechanical
Engineering, University of Saskatchewan (Canada). Reprinted with
permission in May 1982 by Wisconsin Division of State Energy,
Department of Administration, 101 South Webster Street, P.O. Box 7868,
Madison, Wisconsin 53707.
25. "Heat-Recovery Ventilators," October 1985, Consumer Reports
magazine, pages 596 to 599. Consumer Reports, P.O. Box 2480,
Boulder, Colorado 80322.
26. Besant, R. W., R.W. Dumont, and D. Van Ee. An Air-to-Air Heat
Exchanger for Residences, Department of Mechanical Engineering,
University of Saskatchewan, Saskatoon, Saskatchewan S7N OWO
(Canada). These are the original plans for a homemade air-to-air heat
exchanger core, made from polyethylene vapor barrier, plywood spacer
strips, nails, acoustical sealant, and plywood exterior. (This
publication is no longer in print.)
27. Besant, Robert, Rob Dumont, Tom Hamlin, and Greg Schoenau.
Solplan 6: An Air Exchanger for Energy Efficient Well Sealed Houses.
1985. 25 pages. Published by the Drawing-Room Graphic Services, Ltd,
P.O. Box 86627, North Vancouver, British Columbia V7L 4L2
(Canada). A do-it-yourself manual on making a heat exchanger out of
coroplast (special plastic sheeting material), sealant, plywood, and
other commonly available materials. Copies can be obtained from: U
Learn, 126 Kirk Hall, University of Saskatchewan, Saskatoon,
Saskatchewan S7N OWO (Canada).
28. Watson, Donald. Designing & Building a Solar House. Your Place
in the Sun. 1977. 281 pages. Garden Way Publishing, Pownal,
Vermont 05261. The copyright for this text is held by Donald Watson.
29. Insulation Manual. 1971 and 1979. 149 pages. Published by NAHB
Research Foundation, Inc., 627 Southlawn Lane, P.O. Box 1627,
Rockville, MD 20850.
30. McConnel, Charles. Plumbers and Pipe Fitters Library. Welding-
Heating -Air Conditioning. 1977. 374 pages. Published by Howard W.
Sams & Co., Inc., 4300 West 62nd Street, Indianapolis, IN 46268.
The table listing "Ground Temperatures Below the Frost Line" is on
page 60.
31. Mazria, Edward. The Passive Solar Energy Book. 1979. 435 pages.
Rodale Press, Inc., 33 E. Minor Street, Emmaus, PA 18049.
32. Anderson, Bruce. Solar Energy: Fundamentals in Building Design.
1977. 374 pages. McGraw Hill Book Company, P.O. Box 402, Hightstown
NJ 08520.
33. Kreider, Dr. Jan and Dr. Frank Kreith. Solar Energy Handbook.
1981. 1,000+ pages. McGraw Hill Book Company, P.O. Box 402,
Hightstown NJ 08520. Page 16-8 demonstrates heat loss and gain
through double-glazed windows. This reference book is an excellent
source of detailed information about solar energy.
34. Best, Don. "Home Energy Update," October 1986, Practical Homeowner
magazine. Section on Solar energy, pages 74 and 111.
35. Lowe, Carl. "Water-Saving Toilets," August 1986, New Shelter,
pages 26 to 30. The article describes and tests a number of water-
saving toilets. New Shelter magazine was replaced by Practical
Homeowner magazine, which stopped publication in the early 1990s.

References (continued)

36. Butler, Lee Porter. Ekose'a Homes Natural Energy Conserving
Design, 2d edition. 1978, 1980. 112 pages. Ekose'a Inc., 573
Mission Street, San Francisco, CA 94105. When in business, this firm
marketed plans and consultation for the gravity geo-thermal envelope
home and other energy conserving designs.
37. Fleming, W. S., and Associates, Inc. Manual of Acceptable
Practices for Installation of Residential Earth-Coupled Heat Pump
Systems. 1986. 32 pages. Prepared by W. S. Fleming and Associates,
Inc., 5802 Court Street Road, Syracuse, New York 13206. Copyright by
Niagara Mohawk Power Corporation, 300 Erie Boulevard West, Syracuse,
NY 13202. Text was distributed with other data from ClimateMaster
Geo-thermal pumps, 2007 Beechgrove Place, Utica, NY 13501.
38. Heat Pump Manual. EPRI EM-4110-SR. 1985. Electric Power
Research Institute, 3412 Hillview Avenue, Post Office Box 10412, Palo
Alto, CA 94303.
39. Richter, H. P., and W. C. Schwan. Wiring Simplified, 33rd
edition. 1981. 160 pages. Park Publishing, Inc., 1999 Shepard Road,
St. Paul, Minnesota 55116.
40. Hottel and Howard. New Energy Technology: Some Facts and
Figures. 1971. Massachusetts Institute of Technology Press, 55
Hayward Street, Cambridge, MA 02142. This text was the source of the
table on properties of heat storage materials.
41. Nisson, J. D. N., and Gautam Dutt. The Superinsulated Home Book.
1985. 316 pages. $36. John D. Wiley & Sons, 605 Third Avenue, New
York, NY 10158-0012. This book provides a comprehensive coverage of
theoretical and practical considerations in design and construction of
superinsulated houses. This text should be studied carefully before
starting any major energy renovation or construction project.
42. "Cool tubes cooled off." October 1989, Practical Homeowner
magazine, pages 9-10.
43. “Your Roof’s Insulation may have you seeing red.” By Kent
Langholz. This data found by search of the Internet (Sept 2003), in
reference to Phenolic Foam Boards, absorbing water, resulting in
severe roof corrosion. Also shrinkage of the board size over time,
causes loss of effective insulative performance.

Related References

The below listed references contain useful data on energy efficiency
in housing. Although they are not specifically used for information
in this book, they can provide additional clarification of some
concepts of energy conservation.

1. Shurcliff, William A. Super Insulated Houses and Air-To-Air Heat
Exchangers. 1988, 153 pages, $19.95. Brick House Publishing
Company, P.O. Box 134, Acton, MA 01720. This book explains both the
history of energy-efficient housing development as well as the details
of current designs of energy efficient housing types. The book
analyzes causes of indoor air pollution, presents details on air-to-
air heat exchangers, explains in understandable terms the physics of
airflow technology, and describes commercially available air-to-air
heat exchangers.

2. Watson, Donald, and Kenneth Labs. Climatic Design. 1983. 280
pages. $44. McGraw-Hill Book Company, P.O. Box 402, Hightstown NJ
08520. This text provides considerable theoretical detail on the
principles of heat loss and gain in residential houses. Also included
are methods for designing energy-efficient houses based upon local
climate -- sun, wind, temperature, and humidity -- to maintain
comfortable indoor temperatures year-round. Parts of this book seem
inaccessible, except to engineers.
3. A Homeowner's Guide to Insulation and Energy Savings. 1989.
Owens-Corning Fiberglas Corporation, Fiberglas Tower, Toledo OH
43659. This 32-page booklet published by Owens-Corning provides
useful data on installing fiberglass insulation in new construction
and in retrofitting. It provides practical tips for the amount of
insulation to be used and methods of installing the insulation in
attics, walls, floors, and crawl spaces. As of September 1989, this
booklet was available free of charge. Write Owens-Corning at the
above address or phone 1-800-GET-PINK.
4. Your Guide to Windows & Doors, by the editors of Rodale's
Practical Homeowner Magazine. 1986. 30 pages. Practical Homeowner,
27 Unquowa Road, Fairfield, CT 06430, (203) 259-9877. This
publication provides data on window types, framing, glazings, and
special features. It also lists manufacturers who market these
products. Additional data is provided on interior storm windows,
storm window repair, sun control film, new and replacement doors and
door manufacturers.
5. Air-to-Air Heat Exchangers, (brochure FS-191), October 1985, 4
pages. This information can be requested from the U.S. Department of
Energy, P.O. Box 8900, Silver Spring, MD 20907, (800) 523-2929. The
U.S. Department of Energy has information about a number of topics
available to the public.

House Construction Information

1. Holloway, Dennis, and Maureen McIntyre. The Owner-Builder
Experience, How to Design and Build Your Own Home. 1986. 185 pages.
Rodale Press, Inc., 33 E. Minor Street, Emmaus, PA 18049. This text
presents a wide variety of information on house design, planning, and
construction. Additionally, it explains various concepts in energy-
efficient housing.
2. Jackson, Frank. Practical Housebuilding for practically everyone.
1985. 258 pages. McGraw-Hill Book Company, P.O. Box 402, Hightstown
NJ 08520. This text explains housebuilding from the standpoint of a
person who had rarely used tools previously yet successfully built his
own house. It is a "can-do" approach to building one's own house
although the project may seem insurmountable at times.
3. Durbahn, Walter E., and Elmer W. Sundberg. Fundamentals of
Carpentry. Practical construction, 5th edition. 1982. 519 pages.
Van Nostrand Reinhold Company, Inc., 135 West 50th Street, New York,
NY 10020. This book explains the technical aspects of standard house
construction, providing excellent details about wood frame
construction.


Manufacturers and Product Suppliers
(Most of this data is from 1988 through 1992)
1. Furnace and boiler manufacturers (as of 1992)
Below are listed the BTU/hour output of the smallest size furnaces
available for the high-efficiency models. The rated efficiency from
the company literature is included. If lower output furnaces are also
available, the smallest available output with its efficiency is
listed.

Addison Products Company, 215 North Talbot, Addison, MI 49220
Amana Refrigeration Inc., Amana, Iowa 52204
41,000 BTU/hr (gas) @ 90%; 36,000 BTU/hr @ 82%
Bard Manufacturing Company, 520 Evansport Road, Bryan, OH 43506
48,000 BTU/hr (gas) @ 95.8%; 43,000 BTU/hr @ 65%
Carrier Corporation, P.O. Box 70, Indianapolis, IN 46206
61,000 BTU/hr (gas) @ 92.2%; 20,000 BTU/hr @ 70.5%
Clare Brothers Ltd, 223 King Street, Cambridge, Ontario, N3H-4T5,
Canada
Coleman Company, Inc., P.O. Box 19014, Wichita, KS 67204-9014
41,000 BTU/hr (gas) @ 92.1%; 34,700 BTU/hr @ 72%
GlowCore Corporation, P.O. Box 8971, Cleveland, OH 44136
60,000 BTU/hr @ 89% or 91% (gas)
Heat Controller, Inc., P.O. Box 1089, Jackson, MI 49204
45,000 BTU/hr (gas) @ 93.3%
Heil-Quaker Corporation, P.O. Box 3005, LaVergne, TN 37086-1985
38,000 BTU/hr @ 94.7% (gas); 41,000 BTU/hr @80.5%
Hydrotherm, Rockland Avenue, Northvale, NJ 07647
Lennox Industries, Inc., P.O. Box 80900, Dallas, TX 75380-9000
38,000 BTU/hr (gas) @ 97%; 22,000 BTU/hr (gas) @ 68.1%
Magic Chef Air Conditioning Company, 421 Monroe Street, Belvue, OH
44811
39,000 BTU/hr (gas) @ 97.1%; 32,000 BTU/hr @ 74.6%
Rheem Manufacturing, 5600 Old Greenwood Road, Ft. Smith, AR 72906
45,000 BTU/hr (gas) @ over 90%; 34,000 BTU/hr @ 72.2%
Trane Company, 6200 Troup Highway, Tyler, TX 75711
40,000 BTU/hr (gas) @ 95%
Weil-McLain, Blane Street, Michigan City, IN 46360
45,000 BTU/hr (cast iron boilers) @ 85.3%
Williamson Company, 3500 Madison Road, Cincinnati, OH 45209
48,000 BTU/hr (gas) @ 95%; 84,000 BTU/hr (oil) @ 83%
Yukon Energy Corporation, 378 West County Road D, St. Paul, MN 55112
66,000 BTU/hr (oil) @ 90.8%; 40,000 BTU/hr (gas) @90+%



2. Special vapor barrier material and vapor barrier sealants (as
of 1992)

TenoArm film (8 mil, long lasting vapor barrier 9' x 100')
TenoArm seal (to seal the vapor barrier joints)
Resource Conservation Technology, Inc., 2633 North Calvert Street,
Baltimore, MD
21218, (301) 366-1146
Acoustical Sealant (for polyethylene). Tremco, 10701 Shaker Blvd.,
Cleveland, OH 44104
Contractor Sheathing Tape, # 8086 (also suitable for polyethylene and
Tyvek® Housewrap).
3M Contractor Products, 3M Center, St. Paul, MN 55144-1000

3. Housewraps (vapor permeable) (as of 1992)

1) Tyvek ® Housewrap. Dupont, Fibers Marketing Center, Center Road,
Wilmington, DE 19898
2) Barricade Building Wrap. Simplex Products Division, P.O. Box10,
Adrian MI 49221.
3) Airtight-Wrap. Parsec, P.O. Box 38527, Dallas, TX 75238.
4) Rufco-Wrap. Raven Industries, P.O. Box 1007, Sioux Falls, SD
57117.
5) Tu Tuf Air Seal. Sto-Cote Products, Drawer 310, Richmond, IL
60071.
6) Versa-Wrap. DiversiFoam Products, 1901-13th Street N.E., New
Brighton, MN 55112.

4. Blow-in / Foam-in insulations (as of 1992)

1) Air Krete, Inc. (“Air Krete” insulation); E. Brutus Street, P.O.
Box 380, Weedsport, NY 13166, (315) 834-6609.
2) Ark-Seal International Corporation; (“Blow-in Blanket,”
insulation), 2185 S. Jason Street, Denver, CO 80223, (800)
525-8992.
3) CP Chemical Company; (Tripolymer ® phenolic foam), 39
Westmoreland Avenue, White Plains, NY 10606, (914) 428-2517.

5. Reflective insulations (as of 1992)

For a listing of the manufacturers of reflective insulation, write:
Reflective Insulation Manufacturers Association, P.O. Box 2454,
Irwindale, CA 91706 (or search on the internet)

6. Geo-thermal heat pumps (Manufacturers of geo-thermal heat
pumps, as of 1992)

Addison Products, 7050 Overland Rd., Orlando, FL 32810
Bard Manufacturing Co., P.O. Box 607, Bryan, OH 43506
Climate Control Inc., 881 Marcon Blvd., Allentown, PA 18103
ClimateMaster ®, P.O. Box 25788, Oklahoma City, OK 73179
Command-Aire Corp., P.O. Box 7916, Waco, TX 76714
Florida Heat Pump Corp., 601 N.W. 65th Ct., Ft. Lauderdale, FL
33309
Heat Controller, P.O. Box 1089, Jackson, MI 49204
Mammoth Refrigeration, 13120-B County Rd. 6, Minneapolis, MN 55441
Marvair, 3570 American Dr., Atlanta, GA 30341
Thermal Energy Transfer Corp., 1290 US 42 N., Delaware, OH 43015
Water Furnace Int'l., 9000 Conservation Way, Ft. Wayne, IN 46809

7. Foam board covering and adhesives (as of 1992)

1) Styrofoam brand Foundation Coating is designed to cover foam
insulation boards to give it a finish similar to stucco. Styrofoam
brand Construction Adhesive was developed for use with Styrofoam
insulation boards (Dow Chemical Company, Styrofoam brand Products
Dept. P.O. Box 1206, Midland, MI 48674).
2) PL 200 Panel and Foam Adhesive and PL 300 Foam Board Adhesive
(Contech, 7711 Computer Avenue, Minneapolis, MN 55435) is designed
for use with foam insulation boards and will not degrade or "eat" the
foam as some other construction adhesives do.

8. Phenolic foam insulation boards (as of 1992)

1) Koppers Company, Inc., 1901 Koppers Building, Pittsburgh, PA
15219, (412) 227-2000. (They made this product from 1981-1989)
2) Genstar Roofing Products Company, Inc., 5525 MacArthur Boulevard,
Suite 900, Irving, TX 75038, (214)580-5600.
3) U.S. Insulfoam Co. (PhenoliCore brand), P.O. Box 710, 1993 Belford
North Drive, Belvidere, IL 61008, (815) 547-7722.

9. Solar water heaters (as of 1992)

1) Sunflare 2000: Write: U.S. Solar Corporation, P.O. Drawer K,
Hampton, FL 32044.
2) Heat Pipe passive solar water heater: Energy Engineering,
Albuquerque, New Mexico.
3) Solartechnics, 360 Center City, Bangor, Maine 04401

10. Ventilation system accessories (as of 1992)

Filters and wall caps. For wall caps with dampers, it will be
necessary to remove the backdraft damper on the intake cap. X-Change
Air Corporation recommends the wall caps be mounted at least six feet
apart to prevent cross-contamination of airflows.

Broan Mfg. Company, P.O. Box 140, Hartford, WI 53027. This company
also makes Heat Recovery Ventilators.
Model # Description
641 6" duct, Aluminum wall cap with backdraft damper and birdscreen,
$33.95
643 8" duct, Aluminum wall cap with backdraft damper, $45.95

Air Changer (see address under "Heat exchange companies")
Catalog No. Description
OVH6 Two 6" outside vent hoods for intake and exhaust,
includes washable intake filter, $53.00


American Aldes (see address under "Heat exchange companies")
Part No. Description
23014 6" intake or exhaust grille with bird guard, $16.70
22042 6" roof cowl, brown, low profile, $49.40
22036 6" roof cowl, gray, low profile, $49.40
23956 Filter housing for 6" diameter duct, $34.60
23804 Replacement filter for part #23956, $6.80

Star Heat Exchangers (see address under "Heat exchange companies")
7" and 8" duct, Ejection exhaust nozzle. Allows side by side
installation of exhaust and intake without danger of cross-leakage
$25.00
7" and 8" duct, Intake nozzle with bird screen $20.00

Xetex (see address under "Heat exchange companies")
Model # Intake and exhaust hood Model # Intake Filter Housing
HD-4 4" duct size $14 IF-4 4" duct size $15
HD-5 5" duct size $15 IF-5 5" duct size $16
HD-6 6" duct size $16 IF-6 6" duct size $17

11. Blowers and fans that one could use in a homemade air-to-air
heat exchanger. Such items can be purchased from a hardware store, or
from local heating, ventilation, or "electric motor" suppliers. It
may be possible to locate motors of some wholesale fan/blower
manufacturing companies through their distributors or repair people.
Local distributors might be found in the Yellow Pages under "Electric
Motors," "Heating," or "Ventilation." Below are some manufactures of
blowers and fans.

1) Tjernlund Products, 1601 Ninth Street, White Bear Lake, MN
55110-6794; (615)426-2993; 800-255-4208
This company markets duct pipe fans typically available in hardware
stores (as of September 2003). See comments on page 153 about fan
blade shape and airflow problems (and how to resolve them). They are
easily adapted for use in the homemade air-to-air heat exchanger,
described on pages 97-109.

2) Some other sources for duct booster fans, found by search of the
Internet, as of September 2003.
A. Smarthome.com has duct boosters for 4” to 12” diameter ducts.
B. ESP ENERGY; 1615 Newberry; Racine, WI 53402; (262) 681-9288;
1-888-551-9288. Has in-line duct fans for 4” to 12” ducts, plus
several other similar fan versions.
C. Empire Ventilation Equipment Co. 35-39 Vernon Blvd; Long Island
City; NY 11106 (718)728-2143. Has in-line duct fans for 6” to 12”
ducts.
D. Aero-Flo Industries; P.O. Box 358; Kingsbury, IN 45645-0358; (219)
393-3555. Has 6” in-line duct fans.

3) Ancor Industries, 1220 Rock Street, Rockford, IL 61101, (815)
963-7100. (This company apparently out of business, as of 1994.)
This company sold fans easily installed in duct pipes. Their
Superbooster duct boosters were intended for use in heating and
cooling duct pipes to improve airflow to selected rooms. Motors were
low-wattage and were made in 120 Volts (AC), 24 Volts (AC), and 240
volts (AC); sound insulated with foam rubber. I found the 6-inch size
fans very well suited for the homemade heat exchanger (using 14-inch
wide aluminum plates) that I describe on pages 97-109. Below were the
sizes and specifications during the time they were made.

Duct size Model Volts Amps Watts total CFM Price Shipping
5 inch 15-0070 115 V 0.37 15 80 $39.95 $3.00
6 inch 15-0071 115 V 0.40 20 110 $39.95 $3.00
7 inch 15-0072 115 V 0.44 23 150 $39.95 $3.00
8 inch 15-0073 115 V 0.46 25 200 $39.95 $3.00

4) Broan Manufacturing Company, P.O. Box 140, Hartford, WI 53027.
This company makes various ventilation products. (As of September
2003) Broan makes Heat Recovery Ventilators, and has fans and blowers
available as replacement parts for a large variety of ventilation
units they market. Below are listed a few of these fan and blowers
with some related statistical data (from 1990). To vary motor speeds
for these models, model no. 57 solid state infinite speed control, 3
amp capacity ($22.95) is suitable.

Broan Centrifugal blowers
Part # total CFM Used For Model # Price Amps
97006021 100 ventilator 360 $58.60 0.7
97006022 160 ventilator 361 $61.30 1.0

Broan Axial room-to-room fans: Units complete with housing
Part # total CFM Used For Model # Price Amps
6 inch fan 90 Ventilating 512 $33.95 1.0
8 inch fan 180 Ventilating 511 $78.95 1.5

Broan Axial range fans: Fan and bracket only
Part # total CFM Used For Model # Price Amps
97005163 190 range hood 42000 $21.90 0.8 (two speeds)
97005161 160 range hood 40000 $21.20

Broan Twin centrifugal blowers ("dual blowers")
Part # total CFM CFM/stream Used For Model # Price Watts
97006152 200 100 range hood 76000 $46.40 225
97005985 360 180 range hood 88000 $66.80 155
97007542 440 220 range hood 89000 $87.40 270
97006023 200 100 Ventilator 362 $75.70 115
97006024 300/310 150 Ventilator 363, 383 $81.60 165
97007074 960 480 Ventilator 366 $167.90 390

5) Northern Tool & Equipment Co., P.O. Box 1499, Burnsville,
Minnesota 55337-0499. 1-800-533-5545. This mail-order company
occasionally has surplus fans and blowers at a low cost that could
potentially be used in a heat exchanger.

Below are listed other types of fans and blowers made by wholesale
manufacturers. (as of 1992)

1. Howard Industries, P.O. Box 287, Milford, IL 60953. This
manufacturer makes a number of sizes of low-wattage axial fans. The
manufacturer sells only to distributors. Write to the manufacturer
for a listing of distributors. Below are listed a few of the 115 volt
models.

Model # CFM Diameter Watts Price (plus power cord)
2672 70 cfm 4.7" 17 W. $25.74 $1.11
4315 100 cfm 4.7" 19 W. $25.74 $1.11
6052 120 cfm 6.72" 10 W. $52.76 $1.11
5812 180 cfm 6.72" 18 W. $55.54 $1.11
5804 240 cfm 6.72" 30 W. $42.85 $1.11
0101 560 cfm 10.0" 37 W. $55.46 $1.11
Power cord, 24" long, Model No. 6-170-672, $1.11 each

2) Fasco Industries, Inc., Motor Division Headquarters, 500
Chesterfield Center, Suite 200, St. Louis, MO 63017. The
manufacturer sells only to wholesale distributors. It may be
possible to locate some of their distributors or repair people through
the yellow pages. The manufacturer makes a number of different types
of blowers and fans for specific commercial applications. Below are
specifications of a few of the many blowers made by Fasco.

75 cfm, Model B75, 115 V, 0.59 amps.
105 cfm, Model 50757-D500, 115 V, 0.55 amps.
120 cfm, Model 50746-D500, 115 V, 0.72 amps.
160 cfm, Model 50755-D500, 115 V, 1.0 amp.
180 cfm, Model B47120, 115 V, 1.95 amp.
212 cfm, Model A212, 115 V, 1.25 amps.
320 cfm, Model 50756-D500, 115 V, 1.3 amps.



Index


Air exchange rates, 19-21, 86, 87, 104-108
Air-Krete®, 3, 5, 113, 141
Air-to-air heat exchanger, 20, 82-110
schematic diagrams, 21, 82-85
see also : Heat exchangers
Attic access ladder, 131
Attic ventilation, 17, 28, 60, 117

Backward double wall, 32-34, 62, 68-73
condensation, 34, 116
retrofitting, 76-81
schematic, 32, 33
Beadboard, 2, 5
Blowers, 104-109, 142-44
Blow-in Blanket®, 4, 5, 75, 113, 141
British thermal unit (BTU), 1, 35-41, 43-47, 49-50
Building shape
in heat loss/gain, 42, 43

Cellulose insulation, 2, 5
Clerestory windows, 12
Condensation
walls, 6-8, 116-18
windows, 14, 15, 129, 130
Cooling demands, summer, 40-42
Cooling hours, summer, 122, 123
Cooling tube, 27, 48-50, 64
Crosshatch wall, 30, 31, 34, 75
Curtain wall, 33, 68-70, 74-77

Degree-days, 51-57, 122, 123
Design temperatures, 122, 123
Double walls, 30-34

Earth homes, 22-24
Earth tubes, 27, 48-50, 64
Envelope homes, 22, 23, 25-27, 48

Fans, 103-109, 142-44
Fiberglass, 2, 5, 34, 111-14
French seam, 8, 76


Geo-thermal heat pump, 45-47, 142
Ground temperatures, 125
Groundwater temperatures, 125

Heat exchangers, 20, 82-110
company listings, 88-95
coroplast, 96, 97
counterflow, 82-84, 96, 97
crossflow, 82-84, 96, 97
duct system, 65, 108
heat pipe, 85
homemade models, 96-110
rotary, 85, 86
vent plan, 65, 108
Heat loss, sources of, 38
Heat recovery ventilators,
see : Heat exchangers
Heating costs, 54-58
Heating degree-days, 51-57, 122, 123
Heating system, 140-42
sizing the system, 44-47
Heat pump, geo-thermal, 45-47, 140
Humidity, relative, 14, 15, 34, 116-18

Infiltration, 19-21
barriers, 21, 22
Insulation, 2-7, 34, 111-13, 141, 142
cutting batts and rolls, 4
installing layers of, 62
suggested levels, 51-53
types, forms, 2-6
ventilation, 17, 28, 60, 116
Insulative sheathing, 9, 30, 58, 113
Internal gains, 35-40
Isocyanurate foam, 2, 3, 5, 111-13

North, true, 126

Overhang designs, 118-20
proper dimensions, 119-21

Party wall, 30, 31
Perlite, 2, 5
Permeability, vapor, 116, 118
Polyethylene, 8, 9, 67-73, 77-80
Polyurethane (urethane), 2, 3, 5
Pull-down ladders (insulation), 131

Radiant barriers, 3, 5, 16-18, 42, 111-14
in superinsulation, 65-67
installation, 17, 18, 60, 66
Radon, 19, 65
Reflective foil, 3, 5, 16-18, 42, 111-14
Relative humidity, 14, 15, 34, 116-18
Retrofitting, defined, 74
Retrofitting insulation, 74-81, 113, 114
superinsulation, 75-81, 113, 114
Rock wool, 2, 5, 111-13
Roof
framing, 60, 120
windows, 11, 12
R-values, 2-5, 34-40, 111-14

Shower heads, water-saving, 132
Solar gain
examples, 37, 40, 124
gain and loss through windows, 11
tables, 11, 128, 129
Solar home, 22, 24, 25
Solar position, 127
South
deviation from, 126
window gain, 11, 37, 40, 124, 126, 128, 129
Space heating requirements, 39
Styrofoam, 2, 5, 142
Summer heat gain, 39-42
Sun's path in summer in winter, 10
Sun, also see : Solar
Superinsulated house, 23, 27, 28
basement, 70
single-story, 36-42, 68, 69
two-story, 71-73
Superinsulated wall, 62-81, 115
curtain wall assembly, 77, 78
framing, 78
plywood gussets, 77, 80, 81
retrofitting data, 74-81


Temperature gradients of walls, 34
TenoArm film (vapor barrier), 9, 76, 141
Thermal mass, 43, 44
Thermal storage, 47
Thermax foam, 2, 3, 5, 111-13
Toilets, water-saving, 133, 134
Tripolymer ® foam insulation, 3, 5, 141

Urethane foam, 2, 3, 5

Water heating, 132, 133
Windows
clerestory windows, 12
condensation, 14, 15, 129, 130
framing, 14, 63, 64
heat gain chart, 11, 37, 40, 124, 126, 128, 129
insulation, 13, 14
low "E" windows, 15, 16
multiple-pane, 14, 15
orientation, 9-12, 41, 126
shading, 119-21
Winter heat loss, 36-39

Vapor barriers, 6-9, 27-32, 59, 68-73, 77-80
French seam, 8, 76
installation, 59
TenoArm film, 9, 76, 141
Vapor permeability, 116-18
Ventilation, 20, 21, 61, 64, 65, 87, 106-10
insulation, 17, 28, 60, 117
Ventilation system dampers, 108
see also : Heat exchangers, vent plan
Vermiculite, 2, 5







Retrofitting Basement Insulation

Basement walls are subject to excessive winter heat loss when not
insulated. It is possible to reduce basement heat loss significantly
by retrofitting insulation on basement walls and floors.
The technique described here provides a "superinsulated" basement
wall arrangement (about R-27) with basement floor insulation (about
R-6). The basement floor insulation will reduce the final ceiling
height by about 2.5". Before proceeding with basement renovations,
check with your local building inspectors to find out the code
requirements.
1. To serve as the top plate of the basement wall, attach a 2x4 to
the bottom of the first floor joists, so that the inside wall position
will be about 8" from the existing concrete wall. This will provide a
3.5" space between the wall studs and an additional 4.5" space from
the concrete wall to the beginning of the wall studs. The top plate
of the future basement wall should have a piece of polyethylene vapor
barrier (about 16" wide) placed between the bottom of the first floor
joists and the top plate. The top plate can be attached by nailing,
or by pre-drilling holes and holding the top plate in place with 3"
wallboard screws, installed by a 3/8" variable speed reversible drill.
2. It is necessary to seal the space between the floor joists, the
top plate of the (future) basement wall, and the bottom of the first
floor subfloor. This space can be bridged by use of a foam board.
Two-inch-thick beadboard is sufficient for the job. If this is not
available, one can get the necessary thickness of foam board by
obtaining ¾" beadboard and bonding three boards together (a single
thickness of ¾" beadboard is not sufficiently strong). Beadboard
sheets can be obtained in sections ¾" thick by 13 5/8" by 48".
Stagger the ends of the beadboard by ½" when gluing together, as shown
in the diagram on the next page (page 148). This will approximately
match the angle that the beadboard must have when angling upward to
meet the first floor beneath the exterior wall position. The boards
can be glued together using Liquid Nails ® (latex) panel and
construction adhesive. Apply the glue over the surface of one foam
board. Place the second board on top of it in the proper position.
Apply the glue to this surface and place the third board on top of
this. You can prepare a number of these three-section foam boards at
one time. Once all the glue has been applied, place weight evenly on
top of the boards while the glue is drying. (For example, I assembled
about ten of these three-section foam boards at one time; I stacked
them on top of each other and placed some boxes of books and magazines
on top of the stack and allowed a couple of weeks for the glue to set
before removing the boxes.)
3. Once the foam is set, cut it to widths to fit the space between
the floor joists. Wedge the foam board in the space between the floor
joists. Glue it in place around the four sides with Liquid Nails.®
Cover the board with a vapor barrier, ensuring that the vapor barrier
in this space is sealed to the sides of the floor joist, to the bottom
of the first floor subfloor, and to the vapor barrier section on top
of the top plate of the (future) basement wall. I elected to use a
section of radiant barrier* as a vapor barrier, since it has a perm of
about 0.5 and it readily holds in place with caulk and glue; it has
some rigidity and has useful insulation value.
4. The space behind the foam board should be filled with fiberglass
or rock wool insulation. However, allow a day or two for the glue to
set so that you do not force the foam board out of position while
stuffing in the fiberglass. Sealing the space between the floor
joists is a very meticulous and time-consuming project.



*One type of radiant barrier is made as double-sided foil mounted on
building paper -- available from radiant barrier manufacturers such as
R-Fax, 661 East Monterey Ave., Pomona, CA 91767.




See page 151 for further details on retrofitting basement floor
insulation.


5. Sealing around ducts and pipes can be problematic. When
insulating near pipes, make sure you put as much insulation as you can
between the pipe and the exterior wall. If most of the insulation is
not between the pipe and the exterior wall, there is increased risk of
freezing of pipes and drains. It is unsafe to "bury" a pipe within
wall insulation when that pipe is closer to the outside wall--freezing
and rupture could result. Frame around basement windows and add an
additional inside window (sealed to the vapor barrier) when
retrofitting interiorly.
6. Decide whether you intend to install floor insulation. All wood
that directly contacts the basement floor must be pressure-treated; in
the event that moisture seeps through the basement floor, it will not
rot pressure-treated wood. If floor insulation is planned, one
approach is to attach pressure-treated 2x4s (lying flat) around the
perimeter of the basement, with pressure-treated 2x2s spaced every
16”, with two thicknesses of ¾” beadboard (as the floor insulation)
between the wood framing members. (I used masonry nails to attach the
pressure-treated 2x4s and 2x2s – see details on page 151.) Cover the
wood and insulation with a vapor barrier (and a radiant barrier, if
desired) before attaching the ¾” plywood subfloor. The 2x4 wall rests
on the ¾" plywood subfloor. For details on basement floor insulation,
see my narrative on page 151.
7. The concrete basement wall should be covered with a "moisture
barrier" until above grade; this will ensure that water seepage
through the concrete wall will not soak into the fiberglass
insulation. This moisture barrier can be 6 mil or 4 mil polyethylene;
however, the moisture barrier must stop above grade to allow venting
space for any water that gets into the insulation (as by vapor getting
through the vapor barrier) -- such "trapped" water must be allowed to
escape as a vapor. I first nailed ½” thick pressure-treated boards
near the top of the basement wall (above grade) and stapled the
moisture barrier to these boards to hold it in place. The moisture
barrier should eventually be joined to the floor and wall vapor
barrier sections. (Leave enough spare polyethylene to later make that
attachment.)
8. Using a plumb bob for alignment, position the 2x4 bottom plates
(for the stud wall) beneath the previously attached top plate. Then
cut the wall studs to the proper height. Toenail the studs in
position or use metal brackets to secure in place.
9. Fit the 6" batts in the 4.5" space between the moisture barrier
and the row of wall studs. It is best to install the 6" batts at
right angles to the wall studs, starting from the bottom upwards until
the 4.5" cavity is filled. Fit the 3.5" fiberglass batts between the
wall studs.
10. I did a very labor-intensive arrangement on the wall, to place
the wiring and electrical boxes interior to the vapor barrier. On the
2x4 studs I attached the vapor barrier, and sealed it to the moisture
barrier at the floor. Then I attached 2x2s directly to the studs, on
top of the vapor barrier. I found a slightly shallow version of
electrical boxes, which I attached to the sides of the 2x2s. I put
wiring through the 2x2 spaces. Then I attached a radiant barrier to
the 2x2s and put 1x2 furring strips on top of the radiant barrier. (I
pre-drilled holes, and screwed in long screws that went through the
1x2s, the 2x2s, and then into the 2x4 studs.) I spaced the electrical
box position to allow for the additional 1x2 furring strip thickness.
Then I covered the wall with gypsum wallboard.
11. You can then cover the subfloor with tile or carpeting, as
desired. With the basement floor and walls carefully sealed by a
vapor barrier, the final result is nearly an airtight seal, which also
blocks all openings for radon infiltration into the basement.


Getting Started on Retrofitting an Existing Home

Now that you have read all the data in this book, where do you
start?
The first step is to determine the nature and severity of the heat
loss from the house. It is possible to have a professional analysis
of the locations of heat loss, or one can determine the problems by
observation and inspection.
If the house seems drafty, the first step might be to caulk and
weather-strip around doors and windows. If the house is already
fairly well sealed, the first step might be to enhance fresh air
supply prior to "tightening up" the house further.
I moved into a new home, which met the regional energy requirements
for insulation standards. The air quality already seemed poor when
the house was closed up. Since I had earlier completed my homemade
air-to-air heat exchanger, I began to determine the best location to
install this. I was able to route the second floor bathroom exhaust
vents to the basement by converting our "clothes chute" to an exhaust
air plenum. Without such a pre-installed "air plenum," one can route
a 6-inch exhaust pipe (or a rectangular exhaust plenum) to the
basement through a closet space or in the corner of a room and then
cover the duct with wallboard to conceal it. The exhaust air from the
bathrooms is routed to the basement, through a filter, through the
exchanger exhaust fan, through the exchanger, and then through exhaust
pipes to the outdoors. The fresh air is then brought from outside,
routed through a filter; it enters the exchanger and goes through the
fresh-air supply fan and into the basement. At this point it is
possible to provide fresh air supply via ducts to individual rooms.
(This is a very difficult enterprise in a completed home.) I elected
to provide vents between the basement and the first floor rooms. With
an open stairs to the second floor, the fresh air reaches the
bathrooms and hallway exhaust vent for return to the exchanger.
Individual rooms get fresh air when the room doors are open to the
hallway.
While in the attic, I found gaping holes in the attic insulation that
the builders had not covered. My next step was to tighten up the
attic insulation by the following methods. I retrofit a continuous
vapor barrier (see details on page 78). I attached a radiant barrier
to the underside of the roof rafters, from the eaves to the ridge
vent, while allowing venting space above the radiant barrier. I
installed a final insulation thickness of three R-19 batts (R-57
total), except near the eaves where sufficient space was not
available. I did all the attic work in winter to avoid otherwise
unbearable summer attic temperatures. In spring I added continuous
soffit vents and then added ridge vents.
The combination of continuous soffit vents and the ridge vent results
in excellent removal of attic heat in summer. Additionally, the vent
plan reduces the chance of "ice dam" formation in winter. An ice dam
results when the heat of the house warms the roof and melts the snow.
The water from the snow runs down the roof until reaching the
overhang, which is at colder outdoor temperatures. The water is
stopped at the overhang and freezes in an "ice dam." Further melting
of snow causes trapped water at the edge of the roof, which can back
up under the shingles and leak into the attic and house -- causing
significant water damage. Proper attic venting and insulation
prevents this problem.
After the attic insulation/venting project, the next step was
retrofitting basement insulation, as described in these appendix
pages. The basement work is also very time-consuming, yet less
unpleasant than working in the tight spaces of the attic.
If you have an attached garage, sealing and insulating these walls
more effectively can reduce the heat loss between the house and the
garage. The final step in insulation retrofitting may be the exterior
walls. Retrofitting exterior walls will require re-siding the home
once completed. Exterior wall retrofitting can be fairly uncomplicated
for one-story homes with sufficiently wide roof overhangs already
present. With two-story homes or those without sufficiently wide
overhangs, exterior wall retrofitting can be a major undertaking. If
you already have standard wall insulation, exterior retrofitting may
not be economical except in very cold climates or if you have very
expensive fuel costs.


Practical data on retrofitting basement floor insulation

Retrofitting basement floor insulation requires attachment of
pressure-treated framing members to the concrete basement slab. I
used pressure-treated 2x4s around the basement perimeter with pressure-
treated 2x2s spaced every 16" on center as the primary support boards
for the basement floor. I was able to special order beadboard in a
14.5" width to fit between the 2x2s. Alternatively, one could use the
more commonly available 13.5" width of beadboard, and alternate
between 2x2s and 2x4s, on center. I used two thicknesses of ¾"
beadboard between the floor framing, resulting in about an R-6
insulative value. I then installed 4-mil polyethylene on top of the
framing and insulation. I then covered the polyethylene with double-
sided foil radiant barrier. (I used a radiant barrier even though a
reflective air space was not available.) On top of the foil I
attached 4' x 8' sheets of ¾" tongue and groove plywood subfloor. I
then built the walls on top of the plywood, and insulated the
perimeter walls to an 8" thickness, as shown on page 148.
Attachment of the wood framing to the concrete slab can be a lot of
work. The options are (1) using powder-activated nails, (2) masonry
nails, (3) pre-drill the concrete and install plastic anchors,
attaching the wood framing with screws, (4) use a different form of
pre-drilled attachment anchor. The powder-activated nails are quick
and effective; I decided against using them since the device is too
much like a weapon, and occasionally serious injuries have occurred
with use of such "stud guns." I initially tried masonry nails, but
found they would not penetrate our 6-year old concrete without
chipping holes in the concrete and bending the nails. I found plastic
anchors and screws to be fairly effective. However, it is typically
necessary to remove the board to add any additional anchors if the
attachment is not secure enough.
After using some plastic anchors and investigating other anchor
types, I figured that masonry nails might work if pre-drilled in
advance with a masonry bit smaller than the nail thickness. I found
after pre-drilling with a good quality 1/8" carbide-tipped percussion
bit (such as the DeWalt® brand), that the 2.5" Georgia Pacific®
"fluted masonry nails" (which I used for the job) resulted in a strong
attachment to the concrete slab. Typically it took masonry nails
spaced every 16" to firmly attach the 2x2 and 2x4 boards to the slab.
I used a ½" Black and Decker® drill which was equipped with hammer/
drill settings. The "hammer" setting helped the drilling process into
the concrete. After drilling through the wood and concrete for the
full depth of the nail, one should thoroughly suction out the drilling
debris with a "shop vac." It can then take a dozen or more firm blows
with a 4 lb. hammer to drive the nail into the concrete. (The nail
goes through 1.5" of wood and 1" of concrete.) A significant expense
with any pre-drilled method is the cost of the carbide-tipped bits
(about $3 each) which can dull significantly after 10 to 40 holes are
drilled into the concrete. Drilling and hammering into concrete can
be a physically exhausting process, not to mention a very noisy
activity. Both hearing and eye protection are necessary for this job;
knee pads are also advisable. Using Liquid Nails® latex caulk (or
equivalent) under the 2x2 and 2x4 pressure-treated boards enhances the
attachment strength.
To attach the moisture barrier to the inside (concrete) basement
wall, I found it useful to first attach ½" pressure-treated boards to
the basement wall at grade. Use 4 or 6 mil polyethylene sheeting as a
moisture barrier and staple it to the ½" boards to secure it in place,
prior to sealing the moisture barrier to the floor and wall vapor
barriers. (See page 148 for details.) You can attach the pressure-
treated boards to the basement wall by pre-drilling with a masonry
bit, then pounding in 1" masonry nails, spaced every 2 to 3 feet.


Observations on vapor barrier effectiveness

In the winter of 1988 I began retrofitting a vapor barrier in the
unfinished attic of our recently constructed home. I had already
installed the air-to-air heat exchanger in the house a couple of
months earlier, and we had been enjoying the plentiful fresh air it
supplied. As winter arrived, we noticed a dramatic increase in static
electricity in the home; with everything we touched, we tended to get
a shock. It reminded me of my former homes in northern Illinois and
southern Wisconsin, where static electricity was ever-present in
winter -- those homes had little insulation and no vapor barrier. In
our new home, I was installing an attic vapor barrier in the manner I
describe on page 78. I took 3-foot-wide pieces of 4 mil polyethylene
and fit it into the space between the ceiling joists of the upper
floor of the house. I was sealing each 2-foot-wide space between the
joists to the adjacent vapor barrier sections, to retrofit essentially
a continuous air/vapor barrier in the attic. I was closing off
successive sections of vapor barrier, and then moving to the next
section of vapor barrier. On some of the sections, as I closed off
the final seal of the vapor barrier, the vapor barrier began to
inflate with air. I realized I had just closed off a large passageway
for heated house air that typically leaked out of the house. It
seemed to happen most obviously when there were a lot of openings for
electrical wires entering the attic space. Through all of these
drilled holes, large amounts of house air were continuously escaping.
By the time I had gotten half of the attic vapor barrier retrofit, the
static electricity problem in the house was significantly diminished,
and as I continued the project, all static electricity problems ended,
even though the low outdoor humidity of winter remained. All
successive winters have shown no return of static electricity
problems.
The house construction was probably tight enough that we might have
had only mild static electricity problems. With the addition of the
air-to-air heat exchanger, we exhausted a higher proportion of the
stale, moist house air through the exchanger and replaced it with
fresh air (dry, outdoor winter air), which was pre-heated by the air-
to-air heat exchanger. Even with newer, tightly-constructed homes,
much of the house air is lost continuously through unintentional
openings into the attic. Along with this air loss is moisture loss,
making the indoor air uncomfortably dry (resulting in static). By
retrofitting a continuous attic air/vapor barrier, the movement into
the attic of heated house air (and the moisture it contains) is
blocked.

Attic radiant barrier

When I retrofit the attic with a vapor barrier, I also increased the
attic insulation level to 18" (three thicknesses of 6" batts). While
installing the vapor barrier and additional insulation, I also
installed a (double-sided) foil radiant barrier against the roof
rafters in the attic. As I proceeded with the attic project, one
morning I noted an unusual frost pattern on the external roof
shingles. The cold night air left frost on half of the roof -- the
area that I had already insulated; no frost was visible on the roof
over the attic that I had not yet retrofit. Yet the pattern of the
frost ended abruptly -- not explainable by the attic floor insulation
that was several feel below the roof. I then realized that the frost
pattern exactly matched the last section of radiant barrier I had
installed. The radiant barrier was therefore reflecting radiant heat
from the house, back into the house. The areas that lacked a radiant
barrier allowed the radiant heat to escape from the house, to warm the
roof surface and to keep the frost from forming on the roof in that
area. I was able to track the progress of my insulation job from the
outside of the house, as I saw more and more morning frost visible
further along the roof, as more of it had reflective insulation.
Similarly, when the roof gets covered with snow, our roof is about the
last in the neighborhood to melt the snow; this occurs because little
of the house heat escapes to warm the roof. The attic eave vents and
roof ridge vents are also an important part of an effective radiant
barrier. I installed the eave and ridge vents months later, in
spring, after completing the internal insulation work of the attic.
Radiant barriers are known to block the entrance of summer heat into
the attic and house. My observations show there is value in a radiant
barrier, also in cold weather, to reflect escaping radiant heat back
into the house.

Air-to-Air Heat Exchanger -- Update information (as of 1995)

In 1988 I designed and constructed a homemade air-to-air heat
exchanger. (This is described on pages 96 to 109). I installed the
heat exchanger that same year in our new home, using the Superbooster
duct fans as described on pages 109 and 143. After more than 6 years
of faithful service, the intake fan motor wore out. Being unable to
obtain a replacement Superbooster (the company apparently went out of
business), I then replaced the fan with a Tjernlund* fan designed for
6" ducts. I soon found the new fan had a difficult time maintaining
adequate airflow. The motor often labored and ran down to very low
RPMs. This was particularly the case if the inlet airflow was even
slightly restricted. By comparing the Superbooster to the Tjernlund
fan, the main apparent difference was with the fan wheel itself. The
Superbooster fan wheel was made from a circular aluminum disc, cut and
shaped to have 10 pie-shaped blades to move the air. The Tjernlund
fan wheel was a plastic disc, molded to have 4 fan blades. The
Tjernlund fan wheel caused a larger volume of air to move since the
blades struck a much larger area of air per revolution. If the inlet
air was restricted (by filters and bends in the ventilation system),
the Tjernlund fan ran down. Yet under restricted airflow the
Superbooster fan seemed to actually speed up. I found that by
reducing the size of the Tjernlund fan blades, I could prevent the
motor from being overloaded by reducing its airflow capacity to be
better suited for the 6" ducts and filters of the heat exchanger. The
below diagram shows how to trim the fan blades. It is necessary to
make exact measurements and careful cuts (such as by using a coping
saw, and then filing the edges smooth) to keep the fan wheel in
balance for when it is reinstalled on the motor.



When I first installed the heat exchanger, I used a screened inlet to
keep insects out, and then I used an in-line dust filter. Over time,
I found conventional ("furnace") filters are NOT effective in keeping
dust out of the heat exchanger; dust also eventually clogs the fan
blades and motor. I found that ½" thick foam rubber (such as used for
carpet padding or for thin cushioning) makes a very effective filter
for dust. I covered the outside air inlet with ½" foam rubber and
made an additional 10" x 10" in-line filter (using foam rubber) to
keep dust out of the exchanger. I also used the same filtering system
on the exhaust side, prior to air reaching the exchanger. It is
typically necessary to remove the intake filters and clean them (using
soap and water) usually every few months since they get progressively
clogged with dust over time.
I later obtained “filter foam” from a store specializing in foam (and
foam mattresses). The filter foam I obtained in 1-inch thickness. I
now use the filter foam as the in-line air filter. I also use the new
filter foam to replace the previous ½” foam rubber, to cover the
outside air inlet for the air-to-air heat exchanger duct. I use the
filter foam to replace the ½” foam rubber for the inside of the
exhaust air plenum, to block dust from ever reaching the heat
exchanger on the exhaust side.
I also used this type of filter foam to cover the two intake vents
for our whole house ventilation ducts, for the forced air heat
system. (Actually I removed the intake grills, and found I could fit
filter foam inside that location.) I first covered the internal duct
with “hardware cloth” (which is a wire mesh). I put the filter foam
against that wire mesh. The intake air must then flow through the
filter foam, before it enters the ductwork. Now when I clean the
“furnace filter” I clean 3 filters: both of the intake filters AND the
regular filter inside the air handling unit of the forced air heater /
air conditioner. The extra intake filters block additional dust from
entering the forced air ductwork of the house.

* Tjernlund Products, 1601 Ninth St., White Bear Lake, MN 55110-6794