Redesigning John's shop
nick pine
32'
----------------------
| |
| sunspace | 12'
| |
|----------------------|
| |
| |
| shop | 20'
| |
| |
----------------------
Still 640 ft^2 of heated shop space, with a twinwall polycarbonate
sunspace for heat and additional storage/workspace...
More cloudy day heat storage allows less shop insulation.
With 30 cfm of air leaks and 5 3'x4' R4 windows and US Rv walls
and ceiling and floor insulation, the shop thermal conductance
G = 30 + 5x3'x4'/R4 + 2x20'x32'/Rv + (2(20'+32')8'-60ft^2)/Rv
= 45 + 2052/Rv Btu/h-F.
We can heat it to 70 F on a 30 F day with a 1000 Btu/h-F car radiator
with a minimum water temp Tmin = 70+(70-30)G/1000 = 70+0.04G.
If C pounds of water is 140 F on an average January day and it cools
to Tmin while warming the shop for 5 30 F cloudy days, 5dx24h(70-30)G
= (140-Tmin)C makes 4800G = (140-(70+0.04G))C, ie G = 70/(.04+4800/C).
Infinite C makes G = 1750 Btu/h-F, with Rv = 2052/(1750-45) = R1.2
insulation, but that's a lot of water :-)
With N 275 gallon well-insulated recycled totes
http://allentown.craigslist.org/grd/2703253128.html
http://www.youtube.com/watch?v=_MZ9dzBZeFI&feature=related
C = 275x8.33N = 2300N, so G = 70/(0.04+2.1/N) = 45+2052/Rv, ie
Rv = (82.1N+4300)/(68.2N-94.3), eg R106 with N = 2 (Michelin Man),
R26 with 4 (obese, with 6" fiberglass inside 2" Styrofoam), and
R15 with 6 (svelte, with 6" fiberglass inside T111 siding.)
Let's pick R15 with G = 180 Btu/h-F and Tmin = 70+0.04G = 77 F.
~~~
Hmm... 3" Styrofoam under the slab? Can we do this instead?
concreteconcreteconcreteconcreteconcreteconcreteconcrete
foilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoil
wiremeshwiremeshwiremeshwiremeshwiremesh
s meshblock air block air blockwire s
wtre block space block space block meth
paolyethylenefilmpolyethyelenefilmpoolyethyelenefilmpoay
k k
e soil e
~~~
Now how do we keep the water 140 F on an average January day?
L' 32'
----------------------
|-----| |
|T| sunspace | 12'
|T| |
|----------------------|
|4' |
| |
| shop | 20'
| |
| |
----------------------
If the 6 totes are stacked 2-high in 2 north-south rows of 3
in a 4'x10'x8'-tall R30 box in the sunspace with Gt = 304ft^2/R30
= 10 Btu/h-F behind 8L ft^2 of 8'tall sunspace glazing with no air
exchange with the rest of the sunspace and the sunspace is 80 F
for 6 hours and 30 F for 18 on an average day, the tote box will
lose about 6h(140-80)Gt+18h(140-30)Gt = 23,400 Btu/day.
A car radiator can supply 23.4K/6 = 3900 Btu/h to 140 F water during
6 hours in 144+3900/1000 = 147 F air. If 1 ft^2 of R2 glazing gains
0.8x1000-6h(147-34)1ft^2/R2 = 461 Btu/day, we can keep the totes
140 F with 23.4K/461 = 51 ft^2 of glazing, eg 64 ft^2, with L = 8',
and lose 21.7K Btu/day from the glazing to the outdoors.
| W' |
8'
-------------
|-----| |
|T| sunspace | 12'
|T| |
|----------------------
| |
| |
| shop | 20'
| |
| |
----------------------
How much sunspace width W is required to keep the shop 70 F during
an average 30 F day and night? NREL says 620 Btu/ft^2 of sun falls
on the ground and 1000 falls on south walls, with about 420 on east
and west walls on an average 30 F January day in Phila. At 70 F,
the shop needs 24h(70-30)180 = 172.8K Btu/day.
If glazing slopes up to a ridge 8' above the south shop wall with
288 ft^2 of endwalls and 12W ft^2 of ground sun and 16W ft^2 of south
sun, the sunspace collects I = 0.8(288x420+12W620+16W1000) Btu/day.
At 80 F, with Gs = (288-64+22W)/R2, it loses Q = 6h(80-30)Gs Btu/day.
If I = Q + 23.4K + 21.7K + 172.8K, W = 8.4' :-) We might make it 16'.
The shop can be 70 F at dusk on an average day and 60 18 hours later
if RC = -18h/ln((60-30)/(70-30)) = 63 hours = C/180 Btu/h-F, which
makes C = 11.3K Btu/F of room temp thermal mass (eg tools and a slab)
or less higher-temp mass, eg 18h(60-30)180/(140-70) = 1389 pounds of
water cooling from 140 to 70 F overnight in 4 4'x8'x2" trays in
a shelf box to the north of the insulated wall behind the tote box.
Nick
Nathan Hurst
> Hmm... 3" Styrofoam under the slab? Can we do this instead?
>
> concreteconcreteconcreteconcreteconcreteconcreteconcrete
> foilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoil
> wiremeshwiremeshwiremeshwiremeshwiremesh
> s meshblock air block air blockwire s
> wtre block space block space block meth
> paolyethylenefilmpolyethyelenefilmpoolyethyelenefilmpoay
> k k
> e soil e
I think you'd tear the film and have trouble with water pooling in the
gap.
njh
nick pine
> > Hmm... 3" Styrofoam under the slab? Can we do this instead?
>
> > concreteconcreteconcreteconcreteconcreteconcreteconcrete
> > foilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoilfoil
> > wiremeshwiremeshwiremeshwiremeshwiremesh
> > s meshblock air block air blockwire s
> > wtre block space block space block meth
> > paolyethylenefilmpolyethyelenefilmpoolyethyelenefilmpoay
> > k k
> > e soil e
>
> I think you'd tear the film and have trouble with water pooling in the
> gap.
Ken Kern's old Owner Built Home book had a simpler version: spread a
few inches of leaves on the ground, then concrete, then punch deep
holes through the concrete and leaves into the soil (not easy.) When
the concrete fills the holes and cures, the slab is supported by
concrete posts among the layer of leaves, but there's no vapor
barrier, and when the leaves rot radiation makes the air gap without
foil only R1.
Maybe place 8" hollow blocks in a 4' grid on the soil, then place bags
of dry leaves among them, then wire, then concrete over that?
What's fluffy and won't rot if the basement floods? Fiberglass batts
on the ground under poly film under wire under concrete?
Nick
jmygann
John Canivan
is kept dry. Drainage pipe at the base of the foundation helps keep the
gravel dry. Solid insulation on the outside wall of the foundation helps
keep a basement warm. Insulation around the footing will keep the slab from
getting too cold.
John
John Canivan
before poring the cement.
nick pine
> A bed of gravel under the concrete slab acts as an insulator as long as it
> is kept dry.
Material R-Value Per Inch
Sand & Gravel 0.09
http://www.grassroots.ca/homeowner_help_articles/building-material-r-values.php
R15/0.09 = 167 inches of gravel? :-)
Nick