The most recent blogs at Green Building Advisor

The Loophole and the Ozone Hole

Posted on September 5, 2012 by Allison A. Bailes III, PhD in Building Science

Holes are generally bad things. Those of us who teach building science spend a lot of time showing people how to measure the effects of holes, how to seal them up, and why they’re bad in the first place. That’s not universally true, of course. Some holes we do want, but we also want to be able to control what happens in those holes, as with a door or window.

Looking Through Windows — Part 3

Posted on September 4, 2012 by Roger Normand in Guest Blogs

[Editor's note: Roger and Lynn Normand are building a Passivhaus in Maine. This is the seventh article in a series that will follow their project from planning through construction.]

Woe are we with windows!

We started seriously exploring window options in June. Two months later, we are STILL hung-up on windows.

Most people who build new homes go look at window samples in few building supply stores, check the features, open and close the display units, get a price, and quickly decide, “Let’s go with this one.”

Basement Insulation — Part 2

Posted on September 3, 2012 by Marc Rosenbaum in Guest Blogs

In Part 1 of this blog series, I mentioned that I had to move a number of infrastructure items away from the concrete walls so I could have an unbroken insulation installation. In retrospect, it was a good idea to move them, and the time it took was at least partially compensated for by not needing to take time to fit the foam around the obstacles.

They were:

Who Deserves the Prize for the Greenest Home in the U.S.?

Posted on August 31, 2012 by Martin Holladay in Musings of an Energy Nerd

It’s not unusual for an architect to announce, with great fanfare, that he or she has just designed “the greenest home in America” — nor is it unusual for journalists to rush these stories to print. The phenomenon has been going on for years — so long, in fact, that I decided to do a small survey of the “greenest homes.”

Saving a Little More Energy With Exit Signs

Posted on August 30, 2012 by Alex Wilson in Energy Solutions

In the years that I’ve been writing about energy and energy conservation (longer than I really want to admit), I’ve reported on several dramatic transitions in how we illuminate the exit signs in commercial buildings. For an energy geek, it’s been an exciting technology to watch.

Why care about exit signs?
Why do we even pay attention to exit signs—those ubiquitous red or green illuminated signs that direct our escape from a building should the need arise? They can’t use very much energy, can they?

Basement Insulation — Part 1

Posted on August 29, 2012 by Marc Rosenbaum in Guest Blogs

A common truism (that isn't) is “heat rises.” Actually, what rises is air that is warmer than the surrounding air. Anyone who has lived with a wood stove knows this — it's a lot hotter at the ceiling in the room with the stove than it is at the floor. But heat flows from hot to cold, so it readily goes from our houses down into whatever connection they have with the ground, because the ground is cooler than the temperature most of us like our homes to be at.

Looking Through Windows — Part 2

Posted on August 28, 2012 by Roger Normand in Guest Blogs

[Editor's note: Roger and Lynn Normand are building a Passivhaus in Maine. This is the sixth article in a series that will follow their project from planning through construction.]

Grading the Installation Quality of Insulation

Posted on August 27, 2012 by Allison A. Bailes III, PhD in Building Science

Six years ago, RESNET published a major revision of the 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. Standards, officially named the 2006 Mortgage Industry National Home Energy Rating Systems Standards. One important new feature in the standards was the grading of insulation installation quality. Before this change, R-13 insulation installed poorly (as shown in the second photo, below) was equivalent to any other R-13 insulation, including insulation with impeccable installation quality (as shown at the top of this article).

On Shutters and Water Management

Posted on August 24, 2012 by Martin Holladay in Musings of an Energy Nerd

I recently walked through a neighborhood in a Massachusetts town on the South Shore. As you might expect, the homes facing the ocean tended to be more luxurious, while the homes a few blocks in from the beach tended to be more humble.

It’s fun to look at houses from the sidewalk (or, in this case, the beach). During my stroll, I ruminated on house design and construction quality. In this blog, I’ll focus on two themes: the first concerns shutters, and the second concerns flashing and water-management details.

Insulation to Keep Us Warm — Not Warm the Planet

Posted on August 23, 2012 by Alex Wilson in Energy Solutions

I’ve been pretty vocal about a big problem with some of our most common insulation materials: that they are made using blowing agents that are highly potent greenhouse gases.

All extruded polystyrene (XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation.) and most closed-cell spray polyurethane foams (SPF) are made with HFC (hydrofluorocarbon) blowing agents that have global warming potentials (GWPs) many hundreds of times greater than that of carbon dioxide. (My apologies for contaminating this column with so many acronyms!)

Insulation: good news, bad news

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