The most recent blogs at Green Building Advisor

Undamming Rivers Could Make Room for PV

Posted on September 22, 2015 by Karin Limburg and John Waldman in Guest Blogs

Hydroelectric power is often touted as clean energy, but this claim is true only in the narrow sense of not causing air pollution. In many places, such as the U.S. East Coast, hydroelectric dams have damaged the ecological integrity of nearly every major river and have decimated runs of migratory fish.

Solar Decathlon: The Search for the Best Carbon-Neutral House

Posted on September 21, 2015 by Crystal Gammon in Guest Blogs

What’s the latest in well-designed, energy-efficient solar homes? The U.S. Department of Energy (DOEUnited States Department of Energy.) has invited teams from colleges across the country to design and build solar-powered houses that are cost-effective, energy-efficient, and attractive.

Quality Issues With Brick Buildings

Posted on September 18, 2015 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

The design of brick buildings and the quality of brick construction have declined dramatically in the last 100 years. While this statement is debatable, I'll try to defend it with evidence. If my evidence is compelling, it raises questions about why certain technologies advance in sophistication while other technologies decline.

Before I return to the topic of brick buildings, I'd like to take a detour to look at an example of technological evolution.

Ventilation for Your Tight House — Part 2

Posted on September 17, 2015 by Christopher Briley in Green Architects' Lounge

Our conversation with Sonia Barrantes continues. (If you missed it, here is a link to Ventilation for Your Tight House — Part 1.)

We've come to realize that we all want simple rules of thumb to guide our design process. Unfortunately, there isn't a rule of thumb for everything and we're going to have to rely on some common sense, good advice, and good old-fashioned engineering to get this balanced ventilationMechanical ventilation system in which separate, balanced fans exhaust stale indoor air and bring in fresh outdoor air in equal amounts; often includes heat recovery or heat and moisture recovery (see heat-recovery ventilator and energy-recovery ventilator). system right.

Our cocktails are refreshed and we're ready to go.

The Science of Air Flow in Flex Duct

Posted on September 16, 2015 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Sagging flex duct is bad for air flow. We all know it. We all talk about it. It turns out there's research data to prove it, too. Texas A&M did a study a few years ago to look at the pressure drop that occurs for different levels of compression. If you're not familiar with this study, the results may astound you.

Building a Small House in the White Mountains

Posted on September 15, 2015 by Brian Post in Guest Blogs

Editor's note: This is the first in a series of blogs chronicling the design and construction of a house owned by Brian Post and Kyra Salancy.

Should I Skip the Radiant Floor Heat?

Posted on September 14, 2015 by Scott Gibson in Q&A Spotlight

With an R-90 roof and R-60 walls, Jenz Yoder's new off-grid house will be well insulated. Yoder's quandary, outlined at Green Building Advisor's Q&A forum, is whether radiant-floor heat is a good idea.

"I had two consultants tell me that I will not need radiant floor heat, [that] it will be too much," Yoder writes. "We will have a whole-house air circulation system and a gas fireplace. I am worried about not putting in the pipes in the floor and then being wrong."

Flash-and-Batt Insulation

Posted on September 11, 2015 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Closed-cell spray polyurethane foam insulation has several desirable characteristics. It’s an excellent air barrierBuilding assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the interior of the assembly, or both., an excellent vapor retarder, and it has a high insulating value per inch (about R-6 to R-6.5). Unfortunately, it’s also expensive.

Carbon Fees Are Not the Best Solution to Climate Pollution

Posted on September 10, 2015 by David Goldstein in Guest Blogs

Several prominent articles this year that have taken a position against energy efficiency have attracted enough press attention to require formal refutations. But these articles all have something in common: an ideological belief that markets work best unconditionally and therefore that a carbon pollution fee is the "first-best" best economic solution to climate change.

A Few Pressure Testing Tips and Tricks

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

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?

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