Report from our Maine Deep Energy Retrofit

 

My family just spent two weeks of Christmas vacation in the 1850 SF farmhouse we renovated last year. You can learn more about the renovation on that blog. Here is how it performed with a family of 5 plus a couple of extras beds filled from time to time:

Heating:

We heated exclusively with the new Moreso 7642 woodstove in the first floor kitchen. That puts out a maximum heat of 35 kBtu/hr once it’s fully fired up. On cold days (mid teens) with no sun we kept the stove going all the time, and temperatures stayed in the high 60’s. Adding more logs we could have pushed it into the low seventies. When there was sun, regardless of the outdoor temperature, the front (south) rooms of the house got into the mid seventies and we let the stove die down till late afternoon.

What was most satisfying though was the lack of drafts and the even temperatures throughout the house, never varying more than a couple of degrees between attic and first floor spaces. I think the reason has as much to do with the continuous insulation as with the Zehnder HRV which we kept running at low speed distributing the air.

Electrical and solar

We also kept track of electrical use to get a sense of the demand that we will need to fulfill with the solar and battery package that we will be installing in March. With a houseful using the old electric washer and dryer, the old radiant electric heater in the un-restored bathroom, and doing a good bit of cooking and baking on the induction cooktop and electric oven, we burned through nearly 35 kWh/day. That would require an array producing 12,700 kWh/yr to achieve NZE on an annual basis.  I logged one 24 hour period, however, where we did not use the radiant bathroom heater (which is temporary) and the washer and dryer. The energy use plummeted to 15.8 kWh/day, or an annual demand of 5,775 kWh/yr. So once we disconnect the old electric heater and set up winter clotheslines in the basement to supplement summer clotheslines, we will be well under the 8,400 kWh/year anticipated from the array.

 

Batteries

The EnSync Energy matrix will come with two 9kWh Li-Ion batteries for an effective storage capacity of 18kWh. This would give us one day of full use, but as the only really critical loads are the water pump, the furnace switch, and the refrigerator, we should easily be able to go without power for a week in the winter, cooking on the woodstove and playing by ear how much we use the induction stove.