The most recent blogs at Green Building Advisor

Two Solar Decathlon Homes Get High Marks for Affordability

Posted on September 29, 2011 by Richard Defendorf in 2011 Solar Decathlon

The newest of the 2011 Solar Decathlon’s 10 contest categories – affordability – has become an impressive showcase for design ingenuity, and powerful evidence that building energy-efficient homes doesn’t have to bust the bank.

The rules are simple: homes that cost $250,000 or less to build earn the contest category maximum of 100 points, while homes costing more than $250,000 lose points on a sliding scale that tapers to zero at the contest limit of $600,000.

The New ‘Smart’ Grid

Posted on September 28, 2011 by Tristan Roberts in Energy Solutions

I had the honor of being within a few feet of a barn owl this weekend at the wildlife festival at the Southern Vermont Natural History Museum. Kept alive after being injured years ago and now a frequent visitor to classrooms and museums, this bird of prey was perched on the arm of a handler, who wore thick falconry gloves.

What Were They Thinking?

Posted on September 27, 2011 by Carl Seville, GBA Advisor in Green Building Curmudgeon

I’ve been doing HERS ratings and green building certifications for several years now, and I have run across some pretty scary things during inspections that sometimes make me wonder what everyone was thinking.

Now, I was a contractor for a long time, and I understand the challenges of getting things done on time, correctly, and within the budget, and by no means am I trying to minimize those challenges. What does amaze me is how little attention some contractors and trade contractors pay to the details as their projects are underway.

How to Build Efficiently in Massachusetts

Posted on September 26, 2011 by Scott Gibson in Q&A Spotlight

Noah Kaput and his wife seem to be off to a good start in planning their 2,100-sq. ft. house in Massachusetts.

Air Sealing With Sprayable Caulk

Posted on September 23, 2011 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Homes insulated with fiberglass batts are leakier than homes insulated with cellulose or spray polyurethane foam. Until recently, fiberglass batt manufacturers shrugged off the damning air-leakage data, insisting that their batts could deliver the R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. promised on the packaging — and then changed the subject.

Solar Decathlon 2011: Let the Competition Begin

Posted on September 23, 2011 by Richard Defendorf in 2011 Solar Decathlon

For the next several days, “home” for the 19 teams competing in the 2011 Solar Decathlon will be a stretch of the National Mall West in Washington, D.C., that separates the Potomac River from the Tidal Basin.

Twenty-Three Reasons Why I Love GreenITers.com

Posted on September 22, 2011 by Michael Chandler, GBA Advisor in Green Building Blog

When I want to get an inside look at the amazing innovation happening around the world in service of a more sustainable future, I look to Flavio Souza in Tokyo. Souza curates a glorious collection of innovation news and images at his website, GreenITers.com.

Resources for Green Affordable Housing

Posted on September 21, 2011 by Amy Hook in Green Communities

Recently, I have been able to work with the director of Enterprise Green Communities, Trisha Miller, on some local policy conversations. I think I have been roped in because of my extensive work with the public realm through NSP.

An AC Sizing Benchmark for High-Performance Homes

Posted on September 21, 2011 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

One of the most frustrating parts of my job as a Home Energy Rating (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.) provider is dealing with the size of air conditioners installed in Energy Star homesA U.S. Environmental Protection Agency (EPA) program to promote the construction of new homes that are at least 15% more energy-efficient than homes that minimally comply with the 2004 International Residential Code. Energy Star Home requirements vary by climate..

Net-Zero Families, Not Net-Zero Homes

Posted on September 21, 2011 by Tristan Roberts in Energy Solutions

Saturday found me helping a friend install new batteries for another friend's off-the-grid solar power system. We had fun getting the system back up and running and watching the solar-powered watts come in on a beautiful September day.

At one point my friend asked me to use his multimeter to read the voltage of the batteries. No problem: I put the two testing probes in place on the batteries and got the desired reading. He then asked me to reverse the probes to see if the reading also reversed, as expected.

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