26 Apr

Begin with the End in Mind: Our Home Energy Audit

Energy Audit Montage

With our goal of slashing energy costs by 50% over the next two years, we needed to know what we were dealing with in terms of the condition of our house.

We decided to get a home energy audit, which can be a great way to understand the current condition of your home for energy savings opportunities.  In our case, two technicians from St. Louis based Home Green Home spent about three hours in our house. They checked the levels of insulation in the attic, walls, and basement. They used an infrared camera to look for areas of heat loss and inefficiency, and they performed a blower door test to analyze the air exchange in the house. They also provided a report that included suggestions for improvements in order of cost-effectiveness, and a calculation of what our house requires for heating and cooling energy, called a “manual J” calculation. (The Manual J numbers were pretty important to me, because they would help us determine exactly what we needed in terms of heating and air conditioning when it came time to update our existing 20-year-old system. For example, they showed that our current air-conditioner is sized a bit too small, which explains some of our high energy costs during hot periods of the summer.)

Thermal Imaging Test

The thermal imaging camera was not only a fun way to look at the house from a new perspective, but was quite revealing in terms of understanding how hot and cold air move through the ducting and walls of the house. Areas of interest included recessed lighting fixtures, and open channels that run from the attic down to the basement from a (completely unused) laundry chute and around the plumbing stack and family room chimney. We’ll certainly be closing off those open channels, since they represent not only a place to improve energy efficiency, but possible fire hazards and routes for any unwanted pests to move through the house.

Blower Door Test

Blower Door Test

The blower door test involved opening the front door and installing a temporary plastic curtain and a fan that draws air out  to de-pressurize the house.  The technician then measures how much air is exiting to determine how air tight the house is. They look for a number that indicates between 25% and 35% of the air is replaced every hour, and, lo and behold, our house was right at 30%. The tech was so surprised that a house as old as ours was that tight that he ran the test twice, getting the same result both times.

The various tests and resulting reports cost $400, which is fully deductible from Missouri state taxes, as are any upgrades and repairs we make based on recommendations in the report. As I mentioned earlier, since we are planning to replace our heating and cooling system in the near future, an expense of thousands of dollars, I felt that the results of the Manual J calculation alone were worth the cost of the energy audit.

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