Our Whole House Performance Retrofit - Part I (60% savings!)
Thu, June 1st, 2006 @ 2:50PM
In April, Airsmiths Home Performance performed a battery of whole house diagnostic tests on the Folsom house that my wife, Andrea, and I were about to buy. We hired them because we wanted to know how well the home performed in terms of comfort and energy efficiency before we made a final decision on the biggest purchase decision of our lives. We also wanted to know what comfort improvements would be desirable to make and what they would cost so that we could hold back extra cash and finance it into our tax-deductible mortgage.
What We Learned
* The combined gas and electric bills from the previous owners averaged $2,380 for 2005 (peaking at $320 for the month of December--ouch!). Airsmiths estimated the cooling costs at about $500 per year and heating costs at around $1,100 per year at current rates. This amounts to $0.56/ft2/year for heating and cooling. Our last house, four years older and 1650 ft2, was $0.45/ft2. Airsmiths would like to get the Williams Street house down below $0.30/ft2.
* Temperature stratification would be a problem for us in this house. With only the downstairs thermostat calling for heating, the temperature upstairs was 6.6 degrees F warmer than downstairs.
* Some rooms get too little airflow and others too much. The bedroom over the garage will probably by awfully hot in summer, in particular.
* Envelope leakage (leaks through the walls, ceiling, doors and windows) is better than average but there is room for improvement
* Duct leakage is also better than average: 7.4% of the fan flow--the average house leaks over 20 percent of that heated or cooled air into the attic!
* An infrared camera found several notable thermal pathways in the walls and ceiling that could contribute to comfort problems and create pathways for dust, contaminants, and garage car exhaust to enter the home. These included: the architectural arch between the dining room and living room, the knee wall over the stairs, and where the floor plates meet the exterior walls.
* The furnace fan draws more than a kilowatt when running. And it sounds like a jet engine: all air vents emit a considerable rushing noise when their zone is calling.
* The furnace is way over-sized. This is the likely cause of the thermal stratification when the furnace is on--the air coming out of the downstairs vents is so much hotter than the room air that it rises immediately to the top of the vaulted ceiling before it has a chance to mix. Cheap, inefficient grilles combined with high air flow exacerbate this problem.
* Combustion safety tests of the stove and water heater showed carbon monoxide levels are all in the green. This test will be more important when the sealing is complete and the house is tighter.
Overall assessment
This house is not bad as tract houses go, but Airsmiths indicated that there is considerable room for improvement. They think it is possible to get the energy bills down to below what we were paying in the 1650 ft2 house that we are selling, but comfort improvements are what will drive the investments that we choose to make.
What We Learned
* The combined gas and electric bills from the previous owners averaged $2,380 for 2005 (peaking at $320 for the month of December--ouch!). Airsmiths estimated the cooling costs at about $500 per year and heating costs at around $1,100 per year at current rates. This amounts to $0.56/ft2/year for heating and cooling. Our last house, four years older and 1650 ft2, was $0.45/ft2. Airsmiths would like to get the Williams Street house down below $0.30/ft2.
* Temperature stratification would be a problem for us in this house. With only the downstairs thermostat calling for heating, the temperature upstairs was 6.6 degrees F warmer than downstairs.
* Some rooms get too little airflow and others too much. The bedroom over the garage will probably by awfully hot in summer, in particular.
* Envelope leakage (leaks through the walls, ceiling, doors and windows) is better than average but there is room for improvement
* Duct leakage is also better than average: 7.4% of the fan flow--the average house leaks over 20 percent of that heated or cooled air into the attic!
* An infrared camera found several notable thermal pathways in the walls and ceiling that could contribute to comfort problems and create pathways for dust, contaminants, and garage car exhaust to enter the home. These included: the architectural arch between the dining room and living room, the knee wall over the stairs, and where the floor plates meet the exterior walls.
* The furnace fan draws more than a kilowatt when running. And it sounds like a jet engine: all air vents emit a considerable rushing noise when their zone is calling.
* The furnace is way over-sized. This is the likely cause of the thermal stratification when the furnace is on--the air coming out of the downstairs vents is so much hotter than the room air that it rises immediately to the top of the vaulted ceiling before it has a chance to mix. Cheap, inefficient grilles combined with high air flow exacerbate this problem.
* Combustion safety tests of the stove and water heater showed carbon monoxide levels are all in the green. This test will be more important when the sealing is complete and the house is tighter.
Overall assessment
This house is not bad as tract houses go, but Airsmiths indicated that there is considerable room for improvement. They think it is possible to get the energy bills down to below what we were paying in the 1650 ft2 house that we are selling, but comfort improvements are what will drive the investments that we choose to make.
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