Energy Vanguard Blog

High Humidity in a Spray Foam Attic, Part 2

Posted by Allison Bailes on Wed, Oct 26, 2016

Three weeks ago, I wrote about an attic with spray foam insulation and the interesting humidity pattern we observed in it. We placed data loggers near the ridge and floor of the attic as well as in the living space and outdoors. In that last article, I showed the dew point data for the four locations and said I'd come back with more explanation. So here's the followup article I promised.

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Tags: insulation, attic, spray foam, moisture problems, ventilation, heating & cooling

A Few of My Favorite Filter Photos

Posted by Allison Bailes on Fri, Oct 14, 2016

There's really no end to the fun stuff you find when looking at furnace & air conditioner filters. Here are a few of my favorites for this Fall Friday.

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Tags: heating & cooling distribution, heating & cooling

Let's Stop Using the Word "Breathe" for Buildings

Posted by Allison Bailes on Wed, Oct 12, 2016

Breathe. It's a good thing. We need to breathe to live. Breathing consciously relaxes us. And it's a great song by Pink Floyd from the Dark Side of the Moon album.

Breathe, breathe in the air
Don't be afraid to care
Leave but don't leave me
Look around and choose your own ground

Breathing is required of many life forms. But when it comes to buildings, breathing is just confusing.

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Tags: air leakage, moisture problems

Falling Electricity Rates, Bill Tracking, and Energy Efficiency

Posted by Allison Bailes on Fri, Oct 7, 2016

Like many energy geeks, I track my electricity usage and costs. I've been doing it for decades. (Unlike Danny Orlando, however, I haven't stayed in the same house and watched as the home energy improvements kept lowering that usage.) One thing I've noticed in the past few months is that the electricity rate I pay to Georgia Power has dropped significantly. Yesterday, the US Energy Information Administration (EIA) confirmed that falling electricity rates is a (mostly) national trend.

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Tags: environment & sustainability, big picture

Humidity in a Spray Foam Attic

Posted by Allison Bailes on Wed, Oct 5, 2016

Spray foam insulation can solve problems that other insulation materials can't. One of those problems is moving the building enclosure from the drywall ceiling of a home to the roofline. By doing so, you bring the attic inside the building enclosure. But what happens to that attic space when you move it inside? Dr. Joe Lstiburek has been saying for a while now that we can't just ignore the space. He says we shouldn't be calling it a sealed attic or encapsulated attic or unvented attic. We should be calling it a conditioned attic. Here are some data to show why that's true, at least in a humid climate.

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Tags: insulation, spray foam, indoor air quality, moisture problems

The Cost of Solar Energy Keeps Dropping, But...

Posted by Allison Bailes on Thu, Sep 29, 2016

Solar energy has sex appeal. If you want to show the world you're doing something to reduce pollution, you put photovoltaic (PV) panels on your roof to generate clean electricity. Even better, you drive a plug-in hybrid or an all-electric car and charge your car's batteries with your solar panels. The good news for solar enthusiasts is the cost of installing a solar electric system on your home just keeps falling and falling. Let's take a look at some data. Then I'll throw in a little cautionary note at the end.

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Tags: environment & sustainability, big picture, solar energy

7 Things I Learned at the North American Passive House Conference

Posted by Allison Bailes on Mon, Sep 26, 2016

Yesterday I returned home from the North American Passive House Conference. It was great, as it always is. Wait. No, this was the best one yet. On the 10th anniversary of the first conference, PHIUS put on an amazing conference. It was the biggest one ever, I believe. As I flew home I pondered some of the things I heard and saw in Philadelphia and here are few that stood out for me.

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Tags: fun, conferences, Passive House

Grading an Attempt to Get Ducts Inside Conditioned Space

Posted by Allison Bailes on Wed, Sep 7, 2016

There's a ton of new construction and remodeling going on in Atlanta. On a lot near where I live, a developer tore down the old house and is building two new ones. This weekend, I took the opportunity to check out their progress on the first one and saw the mechanical system roughed in on the first floor. They did some good things in their attempt to keep the air handler and ducts inside conditioned space. They also did some not-so-good things. Let's grade their work.

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Tags: design, heating & cooling distribution, heating & cooling

How Dirty Is Your State's Electricity?

Posted by Allison Bailes on Fri, Sep 2, 2016

I've been working on my presentation for the 10th anniversary of the North American Passive House Conference. It's on the global warming impact of insulation, a followup to my latest article about Alex Wilson's work on that subject. One of the things I wanted to do was to see what difference it made when a home used "dirty electricity," with a high carbon intensity, versus a home using "clean electricity." The Emissions & Generation Resource Integrated Database (eGRID) from the US Environmental Protection Agency, has the data I was looking for.

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Tags: environment & sustainability

More on Air Conditioner Sizing Rules of Thumb

Posted by Allison Bailes on Mon, Aug 29, 2016

Air conditioner sizing rules of thumb must die. That's what I wrote in my last article. The most common rule of thumb is to use 500 square feet per ton to determine the size of air conditioner needed. Or 400 or 600 or some other number in that general vicinity. In my article, I showed a graph of air conditioner sizes, given in square feet per ton, for 40 homes that we did load calculations for. The average of the 40 was 1,431 sf/ton. Now, let me say a bit more about that.

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Tags: heating & cooling