The most contentious issue I’ve written about since I started blogging isn’t bad Manual Js. Nor is it endorsing government intervention by raising efficiency standards or improving energy codes. Incredibly, it’s not even whether or not naked people need building science. Nope. The topic that really gets readers hyperventilating is powered attic ventilators (PAVs). Some people swear it’s the best way to keep their attic cool and reduce air conditioning costs. Apparently they haven’t seen the research about what works better than PAVs without the drawbacks.Read More
Energy Vanguard Blog
My friends up in Maine came up with the concept of the Pretty Good House a few years ago, and I love the idea! Not everyone can or wants to build a LEED Platinum, Living Building Challenge, Passive House. But a lot of architects, builders, and homebuyers would like to design, build, and live in houses that are better than the barely-legal, code-minimum houses that populate the market. The Pretty Good House, then, is the way to go.Read More
Building Science Summer Camp was last week. That means I was in Massachusetts with 500 of my closest friends, staying up too late, talking building science out the wazoo, and attending some great presentations from leaders in the world of building science. My big takeaways from Summer Camp this year were Marty Houston's "hairy hand of quality," Robert Bean's three little pigs, and a black toenail. The first was a striking image, the second is the topic of this article, and the third will probably fall off in a few days. (Sorry. If that makes you squeamish, just be glad I didn't tell you how I relieved the pressure.)Read More
I got a question this weekend that's often asked—and, I'm sure, wondered about—by homeowners: "Will my household AC system run more efficiently (perhaps cycle on/off fewer times, or the compressor won't have to run as long when it cycles on) by shading the compressor?" I've written about the outdoor unit of air conditioners and heat pumps a few times, but I've never tackled this question directly. Let's change that now.Read More
Tags: heating & cooling
This time of year, air conditioners are running like mad to keep people cool in their homes. Here in Atlanta, we've had a couple of weeks of hot, muggy weather, with a little break on Sunday. Now we're heading back to the mid-90s with high dew points again. As a result, some people are starting to dread those air conditioning bills arriving and wondering what they can do to save energy. Is the Kickstarter-funded Mistbox the answer?Read More
Psychrometrics, you may recall, is the science that involves the properties of moist air and the processes in which the temperature or the water vapor content or both are changed. To understand how all that works, we need quantities and we need them to be well-defined. Some are easy to understand (e.g., dry bulb temperature and barometric pressure); others are a bit more abstract (e.g., enthalpy). Here we'll take a look at the main psychrometric quanitites, define them carefully, and tell which commonly used term you should avoid.
Your air conditioner does two jobs: It cools down the air and it dehumidifies the air. If you live in a dry climate, you want the AC to dehumidify as little as possible because it uses extra energy and makes you spend more on lip balm and hand lotion. If you live in a humid climate, you really want it to do that second job as well as it can to keep your indoor air dry and comfortable. But where does all that condensate go?
Tags: heating & cooling
I have a confession to make: I've fallen in love with psychrometrics! After water itself, moist air has got to be the most interesting substance in building science. And the psychrometric chart, in all its many manifestations and with its multitudinous quantities, is a thing of beauty. Well, at least it is to me, and maybe it will be to you, too, after you get to know it a bit better.
The Nest Learning Thermostat has been on the market for nearly four years now. One of the biggest things the Nest folks use as a selling point is energy savings. "Programs itself. Then pays for itself." That's the first thing you see when you go to the Nest homepage. But what do the data say? Three independent studies plus a whitepaper from Nest provide some answers.
Tags: heating & cooling
The Nest thermostat has been around since October 2011, quietly collecting data on how your home — and the homes of hundreds of thousands of your neighbors — operates. It gathers information about indoor temperature, relative humidity, air conditioner runtime, auxiliary heat operation for heat pumps, and much more. Unlike the Ecobee thermostat, however, Nest doesn't let its owners see all those data (which is a problem only for energy geeks really). Enter Michael Blasnik.