Sustainability Labs Update 1/23/2012 (Re-posting of GG Community Update)

[Laurie Catey]

The Labs Update to the GG Community Wellbeing Weekly got a little long this week, so thought I would re-publish it here in the Labs forum for our Virtual Labs followers. Hope everyone is having a good new year so far!

Laurie

GG Sustainability Labs

This Past Week:

• In our Labs Session this past week, we reviewed work being done on the Business Plug Load Study, and we made progress on both our Refrigerator Energy Usage and Solar Thermal System Optimization experiments.
• Business Plug Load Study - Information is starting to appear for the various In Residence Businesses laptops as GG Services surveys each one to see how much power they use. We experimented with the Chief MADD Scientist's laptop and the Kill-A-Watt meter and found that the power used by the laptop changed drastically depending on what we were doing. We also found out that when you put the laptop in SLEEP mode, it still draws about 1 Watt of power as it is just in a reduced power state. When you put your laptop in HIBERNATE mode, it turns the laptop off so it is not drawing power. However, if you don't also unplug your AC power adapter, the power supply will still be drawing a little bit less than 1 Watt of power. To truly "turn it off" so there is no power draw, it must be unplugged.
• Refrigerator Energy Usage Experiment - After our phase 1 (winter) monitoring of the Green Garage refrigerator power usage, we had previously reported that at $0.10 per kilowatt hour (kWh), it looks like our annual cost for operating the fridge should be about $5.40. With that under our belts, we are now starting to look at the temperature distribution inside the fridge and helping GG Services to determine where the best place to permanently mount our modified temperature controls is as well as what the best temperature set point would be to balance the power usage with the effectiveness of the appliance.
• Solar Thermal System Optimization - Two weeks have passed since Joe cut back the return line on our solar thermal panel system, which we believe was the reason our panels froze previously, and so far so good on having our system drain properly so it does not freeze up again. We have turned our focus back to optimizing the operation of this system. This week we looked at some great observations that Tom Besemer is collecting on how the system starts and stops as well as beginning to study some temperature recordings (called trend logs or histories) at various places in our thermal storage tanks to see how much stratification we currently have in our tanks. Because we only have one permanent temperature sensor within our tanks and it is used to control the system, we want to understand as much as we can about our actual temperature profile across both tanks so we use our one data point intelligently. We found that the smaller tank appears to be fairly even in temperature, but the bigger tank, where the solar panel water is dumped in at the top appears to have some significant temperature differences from top to bottom. We will be using our temperature controls system to study this further to see how it may impact our control of the system.  Using data loggers, we also found that some of the water heated by the solar panels is bypassing our tanks unintentionally, so we are working on how we might eliminate that issue and pick up some system efficiency.
• Building Systems Commissioning focus this week was on cold weather impacts to our HVAC systems. In order to prevent our Altherma heat pump from tripping out on low flow, about a month ago, Expert Mechanical limited one of our control valves to help keep the flow through our heat exchanger more even, which we determined was our "pinch point" in the system. In doing this, however, it also somewhat limits how much heat we can put out to our radiant floor system. We are trying to figure out if this impact is significant or if it is something we can live with. We also have been keeping our eye on our ventilation system and how cold the air being brought in from outside might get in this deep freeze weather. We have a water coil in the ductwork that can be used to dehumidify the air inside if our humidity gets too high, and in this extreme cold, we are concerned that our energy recovery unit may not be able to keep the ventilation air warm enough to prevent freezing that coil. We are looking at how we might alleviate this condition by possibly manipulating our dampers to blend recirculated air with the outside air to temper it during these weather conditions. More to come!

Next Week:

• Next week, the Labs plan to continue to work on analysis of the temperature distribution and control of our refrigerator. We need to understand a little bit more about the new fridge temperature controller, and then we hope to develop a proposal for finalizing the installation and setup of that controller. We will also continue to analyze what we have learned so far on our solar thermal system while making a plan for another round of data collection on other parts of the system. Tom Besemer will continue to refine his observations on how the system is cycling, and we hope to be able to set up our temperature controls system to trend information more frequently so we can get a picture of the true dynamics of this system as we work to optimize how and when the system is activated and deactivated.
• In Commissioning, we will continue working on the cold weather impacts, as weather permits. We also hope to check calibration on our new Spin Wave wireless space stats. So far they have been staying online and appear to react much better than the ones that they replaced.
• Labs Sessions are held Fridays from 1:30 p.m. to 3:30 p.m. after the Community Lunch and are open to all.
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