Building Science

A Few Pressure Testing Tips and Tricks

Posted on September 9, 2015 by Allison A. Bailes III, PhD, GBA Advisor

A typical BPI Building Analyst spends four to five days in a class learning how to do blower door testing, along with all the other stuff they need to know. HERSIndex or scoring system for energy efficiency established by the Residential Energy Services Network (RESNET) that compares a given home to a Home Energy Rating System (HERS) Reference Home based on the 2006 International Energy Conservation Code. A home matching the reference home has a HERS Index of 100. The lower a home’s HERS Index, the more energy efficient it is. A typical existing home has a HERS Index of 130; a net zero energy home has a HERS Index of 0. Older versions of the HERS index were based on a scale that was largely just the opposite in structure--a HERS rating of 100 represented a net zero energy home, while the reference home had a score of 80. There are issues that complicate converting old to new or new to old scores, but the basic formula is: New HERS index = (100 - Old HERS score) * 5. raters get all that, too, but also have to learn how to do duct leakage testing. Then there’s that whole big bunch of people who have gone through one or two day intensive blower door and duct leakage training for energy code compliance. When they’re done with the training, how do they figure out how to do pressure testing in the real world?

Ten Essential Steps to a Pretty Good House

Posted on September 2, 2015 by Allison A. Bailes III, PhD, GBA Advisor

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 home buyers would like to design, build, and live in houses that are better than the barely legal, code-minimum houses that populate the market.

The Best Way to Keep Your Attic Cooler is to Change Your Roof Color

Posted on August 26, 2015 by Allison A. Bailes III, PhD, GBA Advisor

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.

How to Move Air Quietly Through a Duct System

Posted on August 19, 2015 by Allison A. Bailes III, PhD, GBA Advisor

At my first Building Science Summer Camp in 2011, David Hill gave a great presentation on some of the big problems with duct systems. (In case you weren’t reading this blog back then, I got myself invited with my 2010 article called I Don't Need No Stinkin' Building Science Summer Camp.)

Must the Three Pigs Die?

Posted on August 12, 2015 by Allison A. Bailes III, PhD, GBA Advisor

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.

Relative Humidity Doesn’t Tell You How Humid the Air Is

Posted on August 5, 2015 by Allison A. Bailes III, PhD, GBA Advisor

There's a problem with relative humidity. I hear it a lot when I talk to people about moisture problems. A client with high humidity in his home recently told me he didn't understand how it could be more humid inside his home than it was outdoors. The indoor relative humidity (RH) was 60% while it was only 50% outdoors. Do you see the problem?

The 2015 Solar Cooking Festival

Posted on July 29, 2015 by Allison A. Bailes III, PhD, GBA Advisor

If you've ever wanted to learn how to cook with the sun, the 2015 Solar Cooking Festival in Sacramento was the place to be.

This is the second year of the event, which is hosted by Solar Cookers International. They had quite a variety of solar cookers on display, from simple, two-panel low-temperature solar cookers to large, high-temperature cookers with concrete bases. There was also a cook-off and lots of advice for those who want to learn more.

How Much Will Shading Your Air Conditioner Improve Its Efficiency?

Posted on July 22, 2015 by Allison A. Bailes III, PhD, GBA Advisor

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 Allison A. Bailes III, PhD, GBA Advisor

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 Allison A. Bailes III, PhD, GBA Advisor

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?

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