How a Home Energy Audit Works: Finding Your Heat Leaks
LESLIE: Don in Pennsylvania has got a question about his heating system. What can we help you with?
DON: Yes. I was wondering about a cold-air return – the fresh air return from the – bringing air in from outside …
DON: … the duct work.
TOM: Mm-hmm. You mean, from the exterior. You’re not talking about the return inside the house. You’re talking about venting some fresh air into the house, correct?
DON: Yes. Into the cold-air return ventilation system.
TOM: OK. So, I think what you’re talking about is called an air-to-air heat exchanger and …
TOM: … basically it takes fresh air into the house but allows some of the heated air, as it’s being exhausted – sort of the stale air – to transfer some of its heat to the chilly air coming in and dramatically improves the efficiency of that operation. That’s added typically in a home – a residential home that’s really, really well-insulated; that does not have a lot of air changes per hour, because it maintains the healthy environment. It’s also a fairly standard thing done in a commercial installation, where you have to make sure that you’re always introducing fresh air into the building. So it’s a good idea if the home is very, very tight. If it’s not really tight, then you don’t need to worry about it.
DON: OK. It is a little bit tight.
TOM: Well, how do you know how tight it is? Have you ever tested it?
DON: When I was up in the attic up there, we had the insulation running through the – through the wrappers and across.
TOM: You know, that may seem like it’s an energy-efficient house but we’re talking about how well-sealed the house is. There’s one way for you to tell; it’s called a blower door test. It’s done by an energy auditor and they can actually measure how tight your house is. And I’ve got to tell you, of all the times I’ve seen these tests done – basically, what they do is they stick a big fan in the front door and they blow the house up with air just like you’re inflating a balloon and then they measure how much of it is leaking out and they can actually do it in the reverse, too; they can depressurize the house and measure how much air is leaking in.
Generally, you will find that it’s very, very inefficient; far more inefficient than what you thought it was. So unless you’ve done that type of test, Don, I wouldn’t recommend that you install the air-to-air heat exchanger; just speculating that you may need it. I would get the data first and, frankly, if the house is leaky, you may be better off putting your money into how – in trying to figure out how to make it tighter and that’s something that will also be identified by that blower door test because it will show you exactly what’s leaking; whether it’s the windows, the doors, the walls, the outlets and you’ll know exactly how to attack it and make that house nice and energy-efficient. You can probably get it done, by the way, by your local utility company. They very often offer those services.
LESLIE: Mm-hmm, and sometimes they even do it for free.
TOM: That’s true; sometimes they do do it for free. Don, I hope that helps you out. Thanks so much for calling us at 888-MONEY-PIT.