This year total usage here at the house is 3,808 kWh. Of that, 1,037 kWh went into the Fujitsu heat pump; 861 kWh went to the refrigerator and chest freezer; 598 kWh were used for water heating in the heat pump water heater; 176 kWh used in the range, and 164 kWh by the well pump (dry summer, lots of drip irrigation); lights and plug loads totaled 315 kWh. November and December were just a bit colder than the 5 year average, after a very warm winter last year.
The PV system generated 6,309 kWh, for a net export of 2,501 kWh. We really should be driving an electric car!
This winter I'm re-doing experiments I did last winter, with (I hope) better set-ups. I'm measuring the effectiveness of the Zehnder ComfoAir 200 ERV at recovering heat from the exhaust air and putting it into the supply air. And I'm logging pressure difference between the basement and outdoors, as well as outdoor temperature, and attempting to find correlation with radon levels.
How are you logging pressure differences? I've been wondering a bit whether our ComfoAir is still tuned correctly, and would be interested in doing something similar. I've also started to be a bit more systematic about collecting weather data, and since our heat pump failed we've done some experiments with leaving the house unheated (we left the heat off over Christmas when we were down in Virginia, since we don't like to leave space heaters running unattended).
Posted by: Ted Lemon | 01/02/2017 at 11:12 AM
I’m still stunned at how little electricity you use. Congratulations.
How are you measuring radon level?
Posted by: David Fay | 01/02/2017 at 01:19 PM
@Ted - I'm using my digital manometer (DG700) and Teclog3 on a PC which records minute by minute data. The basement is running slightly negative relative to outdoors - last 9 day measurement was -1.70 Pascals. I did as careful a balance of the ERV as I could, using a powered flow hood and measuring at the inside grilles, and I checked with the manometer at the time relative to the main level and it was almost 0.
@David - I guess it's mostly not having a lot of stuff like entertainment equipment plugged in? Two people conservative with hot water use - 14-15 gpd total. The 15 ft3 chest freezer adds some, and the well pump in the summer uses 10-15 times what we use when we're not drip irrigating. And I think the Fujitsu, set at 70F and left there, is doing very well - maybe COP of 3. Note we occasionally fire up the wood stove for atmosphere when it's cold enough, but we don't feed it to run overnight as we would if we were truly heating the house with it.
I'm using a Radstar 300 to measure radon.
Posted by: Marc Rosenbaum | 01/02/2017 at 05:40 PM
So do you have two manometers that you calibrated together? (I'm really a total tyro when it comes to measuring pressure--sorry for the newbie questions!)
Posted by: Ted Lemon | 01/02/2017 at 11:58 PM
The DG700 digital manometer has two channels, each with two inputs. I'm only using one channel here. One input is open to the basement, and the other input on that channel has tubing that runs outdoors. The manometer measures the pressure difference across the two inputs, in this case basement pressure with respect to outdoors.
Posted by: Marc Rosenbaum | 01/04/2017 at 11:48 AM
OK, thanks! I suppose we could run the tubing out one of the attic holes. :)
Posted by: Ted Lemon | 01/04/2017 at 11:55 AM