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Home Energy Audit

Deeper Dive

US Government Energy Savers
Good site by the US Department of Energy with some very prescriptive steps to check air leaks, insulation, heating and cooling equipment, and lighting. Good blogs from people who followed the steps.

Seattle Government Step-by-Step Guide
A very well-produced, 20-page step-by-step instruction with lots of pictures and diagrams. It was published in March of 2008 so some of the “new stuff” is not as new and the recommended R values are for Seattle area, but a good read with some good background information.

Doug’s Home Energy Audit Report
This is what I got as the final report for the $200 professional BPI home energy audit. It was a basic diagnostic audit that included a blower-door test and thermal camera scan.

Home Energy Audit

The purpose of a home energy audit is to identify ways that you are wasting energy and give you ideas for corrective action. You take the results of the audit and make a prioritized list of changes you want to make. Audits can be simple or complex, but they fall into three categories:

  1. Walk-through surveys where you start with a checklist and walk through the house and make observations using no special equipment.
  2. Diagnostic audits where you take specific measurements of temperature, pressure, and moisture using specialized equipment.
  3. Specialized audits are geared to answering more complex questions about heating, cooling, air distribution, moisture, and renewable energy options.

A basic home energy audit looks for breaks in your house envelope that lets air or heat through. A professional will perform a blower door test with a thermal camera scan to pinpoint and measure the leaks. A more advanced audit will also evaluate the performance of your highest energy consumers. Since HVAC accounts for about 34% of an average home’s energy consumption you may want to add a duct pressure test and HVAC commissioning to make sure that the airflow throughout the house is correct and the refrigerant levels are right.

I invested $200 and had a professional conduct a basic diagnostic home energy audit and love the results. The examination was thorough and took about 3 hours for my 2,000 square foot home. The examiner was certified by the Building Performance Institute (BPI), very experienced, and brought some high-tech gear to get accurate measurements that can be repeated after remediation projects are complete to prove things are fixed.

The inspection started with an interview where we reviewed the energy bills for the last 12 months; inventoried the home of things like doors, windows, bathrooms; and talked about my observations and concerns. He gave me an overview of the audit process and explained the steps that we would be taking during the audit and the timeframe and high-level structure of the report. This took about 20 minutes.

The next stop was the basement. We gathered information about the furnace and the water heater. In my home they both use natural gas so we had to turn them off for the duration of the audit as a safety precaution. The HVAC ductwork and plumbing was inspected. We also looked for signs of water leakage.

The largest part of the audit was the blower door test and thermal camera scan. A large fan device was placed on the front door to blow air out of the house and increase the in-bound air flow of any drafts. We then went around the house from basement to attic using a hand-held infrared camera to find places where air or heat was getting through the walls, ceilings, and floors. Lots of notes were taken as we went from room to room and we talked about what was found and what I could do to fix it. The infrared camera could easily detect cold air coming in around doors, windows, and baseboards. I could see the studs in my wall as cool-spots (the wood studs let more heat through than the insulation). We could also look for mold because it gives off a very low level of heat and would show up as tiny hot-spots. My inspection was done in January and I live near Cleveland, Ohio so the outside air was about 40 degrees cooler than inside the home.

After about a week I received a final report that summarized the findings, estimated the energy use of my appliances, listed actions I could take to make my home more efficient, and estimates for what it would cost to have a professional make the improvements. It was pretty much what I expected. I believe that it was worth having a professional do the audit because:

  1. Found air leaks in the basement, wall corners and around baseboards that I would not have found without the infrared camera
  2. Verified that no mold was growing in basement or attic
  3. Gave estimates for appliance consumption and recommendations
  4. Gave me a perspective of how my home performed compared to others in my area
  5. Tests are repeatable and can measure the improvement after I “fix” the problem

A secondary benefit was 3 hours of consultation with a professional who spends all of his time measuring the energy performance of homes in my area. As I followed Gary around my house we talked about what we were seeing and he answered my questions thoroughly. I had some preconceptions about what we would find and what needed to be done. Some were on track, but others would have been a waste of time and money. You can see my report by following this link. (put link to report pdf)

DIYers can perform a home audit without paying a professional. Instead of a full-door blower and an infrared camera you can use a window fan and a candle or incense to find leaks. Use the Deeper Dive links to the right for more information.