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Energy Vanguard Blog

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Insolation Is Not a Typo for Insulation

 
grandfather mountain insolation insulation solar energy

In 1993 I took a graduate course in solar energy from Professor Yogi Goswami. It was a great course, and one of the projects we had to do was to compile a whole binder full of solar radiation data for Gainesville, Florida. I used an ancient spreadsheet called Lotus 1-2-3 (remember that?) to do all the calculations for various azimuth and elevation angles throughout the year. Another thing I learned in the class was a new word.

The Sad Joke of Higher Furnace Efficiency Standards

 
furnace sealed combustion energy efficiency standard doe

Do you know when the US last raised furnace efficiency standards? It was 1987. Do you know how long the US Department of Energy (DOE) has been trying to change that? At least since 2007. The past eight years have been a sad case of industry heavyweights preventing progress on this important issue. The DOE has just proposed a new rule, so we might finally see some action here. Do you know when it's set to go into effect, if passed?

A Beautiful Solar Home in Utah Nears Net Zero Energy Use

 
near net zero energy home utah 2

I'm writing this on St. Patrick's Day so let me tell you a wee bit about the O'Mearas. Kevin and Svetlana O'Meara live in a beautiful home in Utah that's oh-so-close to being a net zero energy home. After I wrote about how home building is like skiing two years ago, Kevin invited me out to see their home and this year I managed to do so. My wife and I visited them for two days last week and Kevin told me all about the house, including his one major regret.

The Problem of Getting Air for Atmospheric Combustion Appliances

 
hvac furnace atmospheric combustion air building code irc nfpa

Remember those two furnaces I showed you photos of last week? You know, the ones that had ducts placed—or taped, in one case—right in front of them to bring them combustion air. I told you it wasn't a good way to deal with the combustion air issue, but let's go a little further today. Let's look at what building codes say is the right way to do it.

The Energy Vanguard Blog Turns 5

 
blogging about building science five years

On Saturday, the Energy Vanguard Blog turned 5 years old. It's been an interesting and rewarding journey, and I'm really glad I sat down and started doing it in early March 2010.

How NOT to Retrofit a Furnace in a Spray Foam Insulated Attic

 
furnace combustion air intake duct spray foam insulated attic

A while back I wrote about the incompatibility of putting an atmospheric combustion furnace in a sealed attic. Most often the attic is sealed by installing spray foam insulation at the roofline, thus bringing the attic inside the building enclosure and turning it into conditioned space (directly or indirectly). The good news is that some installers understand this problem and seek to address it. The bad news is what some of them do.

Modeling Is Not a Four-Letter Word

 
spacetime curvature modeling experimental data

Energy modeling has gotten a bad reputation in the home performance world. One conference I've attended has gone so far as to say that it's "outside the sandbox" of topics presenters can cover. They want to see data, not modeled results. And they have good reason for that.

The Layers and Pathways of Heat Flow in Buildings

 
fiberglass insulation wall cavity johns manville spider

We used to build houses without giving much thought to heat flow through the walls, ceilings, and floors. The main thing was to provide some resistance against wind and rain, and then we'd get a fire going to try to make the indoor temperatures bearable. If you've ever lived in an old, uninsulated house, you know that method didn't work that well so later we started putting insulation into the cavities in building assemblies. Homes with insulated cavities are much more comfortable, but how exactly does heat flow through building assemblies? Turns out there are two ways.

Should We Change the HERS Reference Home's Energy Code?

 
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The HERS Index is a number that gives you a measure of how energy efficient a home is. We can debate how relevant that number is or how accurate is the energy model it's based on, but the fact is that it's being used. The 2015 International Energy Conservation Code (IECC) includes a compliance path based on the HERS Index, which they call the Energy Rating Index (ERI). Here in my state, Georgia Power has been educating home buyers on the HERS Index since they created their EarthCents program a couple of years ago. But the HERS Index is based on the 2006 IECC. Is that a problem?

New Mexico Green Builders Create Water Efficiency Rating System

 
watersense low flush toilet water efficiency

Energy usually gets top billing in the green building community. It has a huge impact on the environment. We sometimes pay a significant amount for it (although most of us don't pay enough to motivate serious change, but that's another story). We can do energy modeling and home energy ratings. Plus, it's just really interesting! But water deserves a lot of attention, too, and green builders in New Mexico are innovating a way to move water to the fore.

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