Building Science

How Much Will Shading Your Air Conditioner Improve Its Efficiency?

Posted on July 22, 2015 by ab3

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.

Could a Bare-Bones Energy Code Work?

Posted on July 15, 2015 by ab3

Energy codes have all kinds of requirements. You have to have certain R-values in walls, floors, and ceilings. Your windows have to have the right U-values and solar heat gainIncrease in the amount of heat in a space, including heat transferred from outside (in the form of solar radiation) and heat generated within by people, lights, mechanical systems, and other sources. See heat loss. coefficients. The infiltration rate and duct leakage have to be measured and come in below a threshold for your climate zone. And then there are the different pathways for compliance: prescriptive, UA tradeoffs, performance, or HERS Index.

How to Clean an Air Conditioner Condensate Drain

Posted on July 8, 2015 by ab3

An air conditioner does two jobs: It cools down the air and it dehumidifies the air. If you live in a dry climate, you don’t want the AC to dehumidify much 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?

Is Spraying Mist on Your Air Conditioner the Answer to High Bills?

Posted on July 1, 2015 by ab3

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?

Four Ventilation Quotes That Will Take Your Breath Away

Posted on June 24, 2015 by ab3

Looking back over my last several articles, I see that I’ve been going off the deep end. Psychrometrics, hygrothermalA term used to characterize the temperature (thermal) and moisture (hygro) conditions particularly with respect to climate, both indoors and out. analysis of double-stud walls, the physics of water in porous materials... That’s some heavy stuff. So this week I’m going light with some fun quotes about ventilation and indoor air quality.

Fundamentals of Psychrometrics, Part 3

Posted on June 17, 2015 by ab3

In Part 1 and Part 2 of this series of articles, we’ve taken a look at what exactly psychrometrics is and defined the top nine psychrometric quantities. Now we’re going to delve into how we can combine those quantities and create the psychrometric chart.

As you might expect, taking nine variables and putting them into one chart puts a lot of information at your fingertips. It also can take a while to figure it all out. On top of all that, having nine different variables means you’ve got a lot of options for how to show them in a chart.

The Difficulty of Stopping Air Leakage Between the House and Garage

Posted on June 10, 2015 by ab3

A home with an attached garage is usually a home in which people breathe more carbon monoxide (CO). Of course, having an open carport or detached garage is better for air quality (and a feature that usually gets points for you in green building programs like LEED for HomesLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. and EarthCraft House), but what if you don't want to give up that attached garage?

Fundamentals of Psychrometrics, Part 2

Posted on June 3, 2015 by ab3

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 temperatureAir temperature as measured by an ordinary thermometer. 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.

Fundamentals of Psychrometrics, Part 1

Posted on May 27, 2015 by ab3

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.

Does the Nest Thermostat Save Energy?

Posted on May 20, 2015 by ab3

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 white paper from Nest provide some answers. ( first reported on these three studies in a February 2015 news story.)

Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!

Syndicate content