Sunday, January 29, 2012

House heat update & unintended consequences

Fuel Used To Date

With the whole house almost completely insulated, we've burned about 38 cubic feet of firewood this winter, a bit less than 1/3 cord.  (One cord of wood is a pile 4' x 8' x 8', or 128 cubic feet.)  We've been keeping the sunspace between about 50-62F, with the north part of the house generally a few degrees cooler during the day, but dropping to the same temps overnight.  We've made a fire every 2 or 3 days on average.  We made at least 1/3 of those fires for guests or for house showings, not because we needed the heat for ourselves.  We're probably on track to use a total of 4/10 a cord of wood.  We scavenge all our wood for free, but market rate is around $150/cord, so we'll use about $60 worth of wood for heating.

We still have extra heat input from showers (about 3 per week) and from cooking on our gas stove (8 therms=800,000 btus since Oct. 18, or the equivalent of 1/25 cord of wood.) This winter has seemed unusually sunny, so our passive solar heat gain has been higher than in a normal winter.

Future Steps

I'm fairly pleased with our relatively low energy consumption this winter, but we're still far short of our original goal of heating the house entirely from on-site resources.  Some pieces we're still missing:

  • Insulation for all house windows, especially sunspace windows, for better overnight heat retention
  • Finish insulating attic
  • Rocket stove instead of normal wood stove, for much greater efficiency in cooking and heating
  • Install our 5 solar hot water panels and run the hot water through the radiant floor tubing
  • Full growth of trees and shrubs for fuel from pruning & coppicing

Unintended Consequences

In past years, we used our daily fires through the winter to cook our jerusalem artichokes (aka sunchokes), converting the inulin to digestible sugars after 6-8 hours of pressure cooking. That worked well when we made fires daily. Now, with fires only every 2nd or 3rd day, it takes almost a week to cook the 3 pounds of sunchokes which our pressure cooker can hold. Last winter I ate twice that much per week. We could partially solve this problem with an additional and/or larger pressure cooker.

Same problem with processing acorns using our preferred hot leaching method. However, since we don't rely on a pressure cooker, we can "scale up" by using multiple pots of large size to leach the acorns, rather than relying on daily fires.

Similarly, without frequent fires, we're having a much harder time drying nuts, herbs, processed acorn meal, seeds, laundry, wet winter clothes, etc. Now I wish we hadn't sold our solar dehydrator last fall; we could have used it on our sunny winter days when we weren't making fires. If we were staying here longer, we'd probably set up the front porch or carport for initial drying of clothes, moving them inside for final drying as needed. Better yet would be a space protected from rain but exposed to the sun, such as my recent idea of an enclosed greenhouse to the south of our sunspace.

No comments: