Energy Vanguard Blog

Flex duct. It's ubiquitous now in homes with forced air heating and cooling systems. It's easy to install. It's cheap. The installer can show up and rough in a whole duct system without ever having seen the house before and without having a duct design. I'm not saying that's a good thing.

As I sit here on a nice cool May evening, getting ready for my trip to New England tomorrow, I'm thinking about sweat. And that makes me think about air conditioning. It may seem like it doesn't make sense, but when you twist your mind around in just the right way, it does. Really! And what I'm thinking about air conditioning is that maybe we just need to stop talking about how many tons of air conditioning a house needs. Because there's a serious flaw hidden in that kind of talk. Allow me to explain.

Smart people in the home-building industry have a saying about codes: A code-built house is the worst house allowed by law. The implication behind that statement is that if all you're doing is meeting the code, you're probably short-changing the people who will live in the house. The folks at the International Code Council (ICC) are doing their best to make sure that that barely-legal house is worth living in.

We're making progress! With the all the emphasis on energy codes and energy efficiency programs like ENERGY STAR New Homes, more homes are getting Manual J heating and cooling load calculations these days. The intent is that the heating and cooling systems installed will be sized properly because oversized systems have problems (poor dehumidification, short cycling...). But just because an HVAC contractor does a Manual J, that's not a guarantee that the system is sized properly.

I write mostly about buildings and the people who fight about them: the crazy things I find, the good things I find, the super-secret Building Science Fight Club, how I don't need no stinkin' Building Science Summer Camp. Just your standard energy geek fare. Occasionally I talk about peak oil and the Long Emergency. Aside from the few articles I've written about the green home I built, with its greywater system, reclaimed materials, and passive solar features, I haven't said much about sustainable living, though.

It kills me when I see homes getting their windows replaced. No, I'm not referring to the FTC's recent slamming of the window industry for their overblown claims of energy savings. I'm talking about how a large number of window replacements miss a big opportunity that would help ensure they reduce energy usage as much as they can.

I grew up with really bad asthma. Not being able to get enough air into your lungs, in case you haven't experienced it, is pretty scary. I remember lying in bed during one asthma attack, gasping for air, wheezing loudly, and feeling like I was going to die. A trip to the hospital for a shot opened up my lungs again that night, but I continued to suffer asthma attacks even into my mid-twenties. I'm one of the lucky ones who managed to 'outgrow' this debilitating disease, but many live with it every day.

So, you've got a heating and cooling system in your home. There's a metal box outside that makes noise, and you control it with the thermostat on the wall. Can you tell me right now whether it's a heat pump or just an air conditioner? This is a really important question to be able to answer when you're talking to an engineer or contractor at a cocktail party.

Sometimes I find the most amazing mysteries in people's homes, usually in nasty crawl spaces or attics. Here is one such story. The photo at left shows a whole-house dehumidifier. It's tied in with the heating and cooling system, which you can see right behind the dehumidifier. The mystery is in the way it's tied in.

I was rereading one of Joe Lstiburek's articles last week. The man has a way with words (and I'm not just talking about the four-letter ones). This article was called Understanding Vapor Barriers and is perhaps the clearest, most direct explanation I've read on the topic. It's got some nice Joe-quotes, too, of course. Here's one: