Energy Vanguard Blog

How to Choose a Company to Do a Home Energy Audit

Posted by Allison Bailes on Mon, May 2, 2011

Home energy audits should include a Blower Door test in most cases.My two sisters-in-law have been in town the past few days, and one of them needs to get an energy audit for the home she and her husband recently bought in Seattle. I gave her a recommendation for a company to do the audit (from a couple of friends who used to live there), and now she's asking the very reasonable question, "What should I be looking for? What should they do when they come to the house?"

Even though she's a very technically-minded person (she works on nuclear non-proliferation and carbon sequestration issues), like most people, she doesn't know what she should expect when it comes to an assessment of her home's energy efficiency. A good home energy audit these days will cost from a few hundred dollars to over $1000, depending on the size and complexity of the house, so homeowners of course want to know what they're going to get for that investment.

Well, let's dive in and take a look.

Who's Qualified?

Although it may be hard to find someone with one of these certifications in every part of the country, you should look for a home energy auditor who's certified as either a BPI (the Building Performance Institute) Building Analyst or a RESNET certified HERS Rater. Last year I wrote an article about these being the main certifications to look for, and it's still the case.

What Should They Do?

  1. Combustion Safety
  2. Building Envelope
  3. HVAC
  4. Moisture Problems
  5. Detailed Report
  6. Extras

The first thing to know is that there are different levels of assessment. For simplicity, I'll focus mainly on the comprehensive energy audit, but a seasoned home energy auditor can tell a lot just by walking through the house. The key is that it's got to be someone who's already done plenty of comprehensive audits and knows what to look for.

1. Combustion Safety

The motto of BPI is, "First, do no harm…to life, limb or property." If your house has any combustion appliances in it, assessing their safety and suitability should be the first thing the energy auditor does after the initial walkthrough. Often, a home energy auditor is the only person who looks at your house as a system and can tell you if there might be problems such as backdrafting that could put carbon monoxide in your home. A good combustion safety test will include checking for spillage of natural draft combustion appliances, the content of the exhaust gases in furnaces and water heaters, and worst case depressurization of the combustion appliance zone (CAZ).

2. Building Envelope

The building envelope is the boundary between conditioned and unconditioned spaces. It has two key components: the air barrier and the insulation, which need to go completely around the house and be touching each other. The home energy auditor you choose should check all three parts of the building envelope:

  • Integrity of the air barrier
  • Adequacy of insulation levels
  • Alignment of insulation with air barrier

When insulation is installed without an air barrier, it won't do its job. Most types of insulation do not stop air leakage, so one thing the energy auditor will do is look for proper alignment of insulation and air barrier throughout the house.

The energy auditor will also look for proper levels of insulation (wherever visible) and check for the existence of insulation behind walls. They'll check the integrity of the air barrier in two ways: a visual inspection and a Blower Door test. The former tells where the big air leaks are, and the latter quantifies the total amount of air leakage in the house. The auditor can use the Blower Door as a diagnostic tool to locate air leaks, too.


Most homes use more energy for heating and cooling than for anything else, so assessing how well the heating and cooling systems are doing is vital. One thing that a home energy auditor will do that your HVAC contractor may not, though, is look at the quality of the distribution system. It's one thing to heat or cool the air with high efficiency equipment, but if you put that high SEER air conditioner or high efficiency furnace on a crappy duct system, the money spent on the equipment is wasted.

The energy auditor should look at both the equipment and the distribution system. If it's a forced air distribution system, they probably will also measure the amount of duct leakage in each system, especially is the ducts are outside the building envelope. Unless the auditor is also an HVAC technician, they probably won't give you a full assessment of the equipment, but they can tell you, based on the age of the equipment, how soon you might need to replace it.

4. Moisture Problems

There are three things that cause buildings to fail more often than anything else:

  • rain
  • moisture
  • condensation

In other words, it's water. Energy auditors often look for moisture problems in your home and will help find the source so you can eliminate the problem. Most of the moisture problems originate from drainage issues on the outside of the house and should be solved on the outside (e.g., by fixing gutters that dump water at the foundation). Vented crawl spaces are a category unto themselves, and the good news is that we know how to fix them now.

5. Detailed Report

Once the home energy auditor has finished with the onsite assessment of the house, which generally takes three to six hours, they'll write up a report for the homeowners. Some companies have their templates set up and portable printers in their trucks and can deliver the report before they ever leave your house. Most, I believe, will do the report back at their office and then schedule an appointment to deliver it.

The report should cover all the items above (if applicable). It should give the results of the inspections and testing and put them in perspective by comparing what the auditor found in your house to what's required by code (in the case of insulation mainly). In the case of infiltration and duct leakage, the comparison is usually to a scale showing what's good and what's bad. With the former, they may also tell you what size hole you have in your house.

Finally, with a good home energy audit report, you should get a scope of work that prioritizes the improvements you could make based on their cost effectiveness. Air sealing and duct sealing are usually at the top of the list of energy improvements, though combustion safety issues trump energy efficiency.

The report may also list any rebates and tax incentives that you can qualify for by improving the energy efficiency of your home. These vary by location, and not every home energy auditor can qualify you for every rebate. For example, Georgia Power has a generous rebate program, but you have to use one of the approved assessment contractors to qualify for them. To find out what's available in your area, you can check the DSIRE or Tax Incentive Assistance Project websites.

6. Extras

Some other items that your home energy audit may include are a look at your home's:

  • Thermal imaging with an infrared camera
  • Water efficiency
  • Lights and appliances
  • Dryer vent
  • Energy bills
  • Financing options

Some companies include thermal imaging with all or most of their audits, and some don't. It gives a good auditor another way to look at a house and find some things that they might otherwise miss. It requires adequate training to get meaningful results and can be abused, but it's another tool that can really help.

Some energy audit companies will check the flow rates of your faucets, toilets, and shower heads and make recommendations for improvement. Some check your lights and appliances and can even measure energy use of items like refrigerators with devices like the Kill-A-Watt or the WattsUp. I wrote about the dangers of underperforming dryer vents a while back and gave some recommendations for improvement there. Some energy auditors will check that as well.

When I was doing energy audits (or home performance assessments, as I called them), I included an analysis of the homeowners' energy bills. If they could give me 12 months of their bills, I could plug it into a spreadsheet I'd put together and calculate their energy intensity, the energy use per square foot of conditioned floor area per year.

If your intention is to use a home energy audit as a guide to improving your home, then hiring an auditor who can help you with financing options could be a big plus, too. Perhaps the best one available, in my opinion, is the Energy Efficient Mortgage, which you can use either for a purchase or a refinance.

Choosing a Home Energy Auditor

So there you have it. You can use the above information as a guide to choosing a home energy auditor and making sure you get the most bang for your buck. As with any other contractors you bring into your home, you should also ask for references and check them. I'm sure the comments below will have even more good advice.

Two things to be wary of are the 'free energy audit' (usually offered by companies who just want to get into your house to sell you their product or service) and the yahoo who bought an infrared camera and thinks it can find everything. Use the guidelines above to choose a home energy auditor, and you'll get a much better audit.

If you're in the Southeast, check our list of certified home energy raters to see if there's one in your area. Many of them have both the HERS Rater and BPI Building Analyst certifications.

Tags: RESNET/BPI, HVAC, building enclosure, insulation, air leakage, moisture problems, diagnostic/performance testing, water heating, health & safety