What’s in an Energy Audit?

Our homes are a great place to start when lowering our carbon footprint. In fact, there are lots of things we can do for our homes, which are energy efficient or environmentally friendly, that have little to no impact on the aesthetic value of the home and come at little to no cost to you. But where to begin? The infamous energy audit of course. I say infamous because there is really no standard for an energy audit. Most homeowners don’t know what they should be looking for when they ask for one, and so most don’t really receive any valuable information about their home once they complete one. Follow along with me, and I’ll explain what all of us should be asking for.

Let me start out by explaining why an energy audit is necessary in the first place. For one, there are a million products out there claiming to be energy efficient and/or green. And while many of these products and their installation providers can make magnificent claims regarding performance, not all products will react the same way in all houses, all climates, and even for all operators. Second, your house works as a system. Changing one thing about your home without addressing others not only has the potential to yield poor results, but can actually create an unsafe indoor environment in the home. Not to mention some advertised energy efficiency upgrades on things like appliances can inversely affect the output of other appliances, effectively negating the expected results on the utility bill. This is typically why most people stray away from efficiently updating their house, or have been extremely unsatisfied with the “greener” products they’ve purchased. But an energy audit is a very helpful tool to use prior to investing in any upgrades, it should allow you to measure the synergy between all your household energy uses and prioritize them. Even if you’re sure it’s your windows which leak like a sieve, it’s important to find out what changing your old windows will do to your indoor air quality, your furnace, and air exchange among other issues. Remember you cannot change one thing without changing the performance of everything. In other words, by changing your windows, you have tightened the structure, which means you won’t need as large a furnace, and without changing your furnace to a smaller size you typically will see no drop in your utility bill.

So what’s in an energy audit? Well, for starters there are a few organizations which teach whole house energy audits and testing. They are the Home Energy Rating System (provided by RESNet), the Building Performance Institute, The Comfort Institute, and the Leadership in Energy and Environmental Design (LEED provided by the USGBC). All of them require at least the use of an infiltrometer blower door as well as some way to measure duct leakage, which in turn is calculated through a software program. If you're not using a company which is a member of one of the aforementioned organizations, make sure they are at least providing a blower door test. Other tools used, however, are duct blasters, combustion analysis, infrared cameras, and static pressure manometers to name a few. Now don’t worry if you’re not quite sure what all of this is, because I’m going to tell you what you need to know by the end of the audit.

A good energy audit should last about three to four hours in the home (it will be shorter the less square footage you have). Also, a good energy audit should provide you with a minimum of the following information:

1) An exact air exchange rate based on ASHRAE, which sets the ventilation standards for buildings. This number will tell you if your home is too tight and needs more ventilation before sealing the home further. You will need this prior to changing out windows, performing any weatherization, and even upgrading insulation.

2) A duct leakage measurement. This will tell you how much air is being lost or gained to the outside through your duct work. Because ducts are mechanically pressurized, they can be the greatest energy loss in the home. You will need this prior to upgrading your furnace.

3) Insulation measurement. This will tell you, along with the air exchange rate, whether you have enough insulation for optimum efficiency and whether you have any infiltration from the outside through your insulation. You will need this prior to adding an air seal and/or adding new insulation.

4) An infiltration tour of the home. Your auditor should allow you to follow them through the house, while the blower door is running, to spot where airflow is coming in at. The auditor should have some kind of smoke generator or even an infrared camera to help illustrate where the air is coming in at. This along with the air exchange will allow you to accurately pinpoint where you should tighten your home.

5) A combustion analysis. This will let you know that all of you gas appliances are venting properly. The auditor may also tell you how much energy is being wasted through draft-vent gas appliances.

6) A static pressure test on your duct work. This will tell you how well air is balanced from one room to the next and why hot and cold spots persist in the house.

7) If an auditor is really good, they will also perform a Manual J heat load/loss calculation on the home. This will tell you whether your heating and cooling equipment is correctly sized for the house.

8) And if an auditor is exceptional, he should also evaluate your landscape water usage.

9) And at the end of it all, your auditor should be able to discuss with you the various efficiency upgrades you can make (many of them you should be able to perform yourself) and help you make a priority of those upgrades based on safety, budget, and indoor air quality requirements.

Notice that I didn’t list kitchen appliances, like refrigerators and microwaves, or Energy Star listed electronics, like your television or computer. I didn’t list any of these consumer goods, because they aren’t typically the energy issue in the house. I mean, unless you’re running a large sports bar out of your house with several big screen televisions running at the same time, only a small portion of your energy bill is spent on running your television. Remember, 70% of your bill (on average) is spent on heating, cooling, and hot water, so taking care of those issues is typically a priority. Also, I didn’t list electronics because you do not need an energy audit to tell you how much energy a consumer good, like a refrigerator, is going to use or is using. That information comes on the box or can be found on the data plate attached to the product. Also, electronics and kitchen appliances don’t change with their environment. Meaning they will use the same amount of energy in Florida as they do in Wisconsin. Your furnace or air conditioner on the other hand may not only work different in different regions, but from one house to the next in the same neighborhood.

Don’t go it alone. Unless you test, it’s just a guess. Find out all the facts before making any decisions on efficiency or environmental improvements. Although there’s typically a cost to an energy audit, it’s well worth the peace of mind you’ll have in knowing not only what the real problems in your home are, but also that you’re making the right decisions in any improvements you decide to proceed with. Nothing’s worse than wading through a million “green” options, and then investing in one that doesn’t yield the results you expected.

You can watch a quick video about a good energy audit, produced by The Comfort Institute at www.climatebydesign.com/videos and click on "Whole House Test."