The most recent blogs at Green Building Advisor

Blower Door Basics

Posted on January 29, 2010 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Leaky homes are hard to heat and hard to cool. The only way to know whether your home is leaky or tight is to measure its air leakage rate with a blower door. A blower door is a tool that depressurizes a house; this depressurizationSituation that occurs within a house when the indoor air pressure is lower than that outdoors. Exhaust fans, including bath and kitchen fans, or a clothes dryer can cause depressurization, and it may in turn cause back drafting as well as increased levels of radon within the home. exaggerates the home’s air leaks, making the leaks easier to measure and locate.

An energy-efficient house must be as airtight as possible. Many older U.S. homes are so leaky that a third to a half of the home’s heat loss comes from air leaks.

CODE TIP: Footing Drains and Foundation Waterproofing

Posted on January 27, 2010 by Daniel Morrison in Code Green

Building codes require perimeter drains around the outside of basement footings. They are not difficult to install properly before the foundation has been backfilled, but they are costly and disruptive to put in after the fact.

Sections 404, 405, 406, and 801 of the International Residential Code (IRCInternational Residential Code. The one- and two-family dwelling model building code copyrighted by the International Code Council. The IRC is meant to be a stand-alone code compatible with the three national building codes—the Building Officials and Code Administrators (BOCA) National code, the Southern Building Code Congress International (SBCCI) code and the International Conference of Building Officials (ICBO) code.) relate to foundations and below-grade habitable space. All code references are to the IRC unless otherwise specified.


Tax Credits for Energy Upgrades

Posted on January 26, 2010 by Alex Wilson in Energy Solutions

There are some great opportunities right now to upgrade your home energy performance with support from federal tax credits. These tax credits, created as part of the American Recovery and Reinvestment Act of 2009 greatly expanded tax credits that had been put in place through the Energy Policy Act of 2005 (EPAct). Over the next few weeks I’ll describe these tax credits--addressing what they cover and how you can benefit--but also editorializing a bit about some of the poorly thought-out features.

A Contrarian View of Passive Solar Design

Posted on January 26, 2010 by peter powell in Guest Blogs

By Peter Powell, AIA

I have designed over 60 passive solar homes over the last 35 years and have lived in seven of them. Based on that experience, I have come to a few conclusions which, although contrary to conventional passive wisdom, I have found to be valid. I must qualify these comments by saying that most of my experience has been in the Northeast, primarily in Maryland and Pennsylvania, in areas with 4,000 heating degree days and up. The following comments mostly apply to new construction in similar or colder climates.

Ramblings from the Builders' Show

Posted on January 24, 2010 by Carl Seville, GBA Advisor in Green Building Curmudgeon

IBS this year was refreshingly downsized from the behemoth that it had become over the past several years. With attendance in the range of 100,000 a few years ago and enough demand for exhibit space to outstrip the capacity of all but the largest convention centers in the country, this annual conference became a test of endurance for anyone attempting to see everything on display. Even though attendance of about 55,000 this year (roughly the same as last year) was disappointing, vendors and attendees seemed more optimistic than in 2009.

Rural Vermont Outsulation

Posted on January 22, 2010 by Martin Holladay, GBA Advisor in Green Building Blog

My grandmother grew up in a sod house in South Dakota, and she often used to tell me about one of the chores she performed every fall: banking the home's walls with horse manure to help keep the family warm. In rural Vermont, the usual method of banking houses involves hay bales — in some cases supplemented with polyethylene or blue tarps.

When I moved to Vermont in 1975, I could get mulch hay for free. Now farmers sell hay for $3 a bale — even spoiled hay that's only fit for mulch. As hay gets more expensive, rural residents are turning to more modern materials to bank their walls.


Posted on January 22, 2010 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

After investigating various ventilation options, many residential designers conclude that they want either a heat-recovery ventilator (HRV(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. ) or an energy-recovery ventilator (ERV(ERV). The part of a balanced ventilation system that captures water vapor and heat from one airstream to condition another. In cold climates, water vapor captured from the outgoing airstream by ERVs can humidify incoming air. In hot-humid climates, ERVs can help maintain (but not reduce) the interior relative humidity as outside air is conditioned by the ERV.). They often remain confused, however, about which of the two devices to choose.

Every tight home needs a mechanical ventilation system.

Does Building Green Cost More?

Posted on January 21, 2010 by Daniel Morrison in Green Building Blog

As you know, I posted a survey the other day asking for feedback from folks who use Green Building Advisor. At the end of the survey I asked a couple of open-ended questions in order to get some comments. While not nearly enough of you have filled out the survey (if you don't vote, you can't complain), a couple of good comments came in. Thanks for filling out the survey and sharing your thoughts with us.

One comment, I think, can make a good conversation starter.

Can a Kitchen Downdraft Fan Be Connected To an HRV?

Posted on January 21, 2010 by Daniel Morrison in Q&A Spotlight

Powerful kitchen exhaust fans do a good job of removing cooking odors and smoke. They also have the potential to depressurize a house, causing water heaters to backdraft and pulling ashes out of the fireplace and onto the hearth.

Help Us Get Better

Posted on January 20, 2010 by Daniel Morrison in Green Building Blog

Today we're one year old!

Thanks to all of you who have registered for Green Building Advisor, and to those who have signed up for PRO membership — thanks for paying our salaries.

To help us better understand who you are, what you want, and how we can help you more effectively, please take a few minutes to fill out this short survey.

The link takes you to, a web-based survey service, so don't be alarmed that you're leaving Green Building Advisor.

Thank you very much for your help,

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