Thursday, December 17, 2009

1 Year Report on Gordon's Deep Energy Retrofit

A few months ago, Gordon and Sue sent in a very complete description of their project to completely remodel a poorly insulated and drafty schoolhouse for their residence.  There goal was to bring it up close to Passive House Institute standards.  Through a combination of an external Larsen Frame insulation scheme, added sun space, much sealing, excellent windows, and passive solar gain additions, they have achieved their goal.
The new sunspace added as part of the retrofit.

Gordon sent in the report after one year.  It covers performance to date (very good), and some fixes they have made to some problems that have come to light while living in the new home.

The very detailed report on the original project, including report, many pictures, and thermal analysis spreadsheet...

The 1 year update report, including performance to date, problem fixing, and updated thermal analysis spreadsheet...

This is the most carefully planned and executed energy retrofit I have seen, and it's really nice to see it living up to expectations.



  1. "Passive solar" is often direct gain mass and glass, which comes with a dilemma: lots of windows on living spaces lose lots of heat at night and on cloudy days.
    Could Gordon and Sue achieve a 90% solar heating fraction with less wood burning if they converted most of their south windows to simple passive air heaters in December and January by pushing 4" polyiso boards into the frames with an air gap between the darkened board surface and the window and a slot at the top but no slot at the bottom? (If so, they might change to windows with higher U-values and solar transmission.)
    A fancier and more efficient indoor panel might contain some dark window screen and a flow organizer at the top.

  2. Yes Nick. It is a nice looking passive solar home with a lot of thermal mass. I understand that most of the heat gain will be lost through the glass and a good way to prevent this would be to transform the mudroom glazing into a modified tromb wall in the winter, but I doubt Gordon will want to give up his sun room.
    Too bad that the fan and ductwork used to extract heated air from the sun room is so small.
    BUT the main thing that's impressive about this house is the thermal mass and the super insulation. The sunroom is isolated from the rest of the house so the heat loss from this room would be minimal. It's the other rooms that I'm concerned about.

  3. Hi Nick and John, thanks for the comments. I like your ideas, but the daylighting is wonderful. The window wells are 17" deep so it may well be feasible to have folding units hinged to the sides so that they might be fully closed, 50% closed or fully open. Door & window loss is only about 14% of total. Increasing window R to R30 might drop door & window load to 3% but 1" or 2" foam is likely to be easy to design and construct very inexpensively. My big thermal losers are my slab at 28% which would have been very costly to upgrade and ventilation/infiltration at 30% - something I would like to take a second look at - but after building a solar water heater!
    Nick, we don't need a 90% solar fraction to break even, I figure moving from 50 to 68% would do it. As it is, the boss likes the fire for bread baking, and is already shagrined, that we don't have them 7 or 8 months of the year!


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