The next spring our First time home buyer 0% interest loan (we got in before it was a full blown tax credit) was put to some use. Dirk & Trevor Fyffe installed a 40,000 btu American Standard furnace with an AFUE of 95. They also installed the new thermostat. I also did a little air sealing in the attic. Mostly along the bathroom wet wall and the top plate going down the middle of the house. Dirk & Trevor had also re-wired the old knob & tube, so those holes were also sealed. All told, the attic went from a 45 Pa pressure difference with reference to the house, to about 49 Pa pressure difference. I also had the box sills and crawl foundation walls foamed. About 3" in the box sills and about 1.5" on the crawl walls. The house was also used for building technician certification events. Meaning the uninsulated sidewalls had dense pack cellulose installed. After all that, the house's blower door reading is about 2300 cfm @ 50 Pa.
Notably missing from the efforts are the following:
- No new windows were installed.
- No new doors were installed.
- No additional attic insulation was installed
So I still have the windows from the 1920s when the house was built (albeit with leaky aluminum storms). The two doors are metal with foam insulation & storm doors. And I only have an average of about 2" of old rockwool insulation in the attic. Which resulted in the following savings the next winter:
The annual usage went from 772 therms down to 494 (+/- 12) therms. A savings of 278 therms (36%). The energy intensity dropped to 6 btus/sqft*HDD.
During this time, there was a 6 degree setback in the t-stat. So that is the baseline for my next experiment. Data is currently being collected using a 3 degree setback to see how that changes the house's energy consumption.
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