The most recent blogs at Green Building Advisor

Sealing Ducts: What’s Better, Tape or Mastic?

Posted on August 6, 2010 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Most residential duct systems have numerous leaks that waste energy and lead to room-to-room pressure imbalances. Unfortunately, though, few building inspectors outside of California bother to enforce existing code requirements that residential duct seams be sealed with mastic or high-quality duct tape.

Westford Building Science Symposium Raises Some Interesting Questions

Posted on August 6, 2010 by Carl Seville, GBA Advisor in Green Building Curmudgeon

Much of the GBA team was in attendance at the 14th-annual Westford Building Science Symposium last week. More commonly known (and maybe more accurately described) as “Summer Camp,” this invitation-only, three-plus days long assembly of several hundred people involved in building science is a geek's delight, featuring long days of lectures followed by dinner, drinks, and music until the wee hours. How we manage to get up and function each morning is one of the biggest mysteries at camp. If any Twitter fans are interested, look for #bscamp in tweets from this week to learn more.

Vapor Profiles Help Predict Whether a Wall Can Dry

Posted on August 5, 2010 by Peter Yost in Building Science

Today’s walls, roofs, and floors are better insulated, tighter, and made with a much greater variety of components than they used to be, making them a lot more susceptible to moisture problems when they get wet. Compared to the old days, today's walls and ceilings are more complicated and can be very slow to dry.

Can Heat Be Stored in a Sand Bed Beneath the House?

Posted on August 4, 2010 by Scott Gibson in Q&A Spotlight

David Meiland was intrigued by something he'd read in a Breaktime post at Fine Homebuilding magazine in which a Minnesota builder discussed plans for a heat-storing layer of sand 4 ft. thick below the house slab.

PEX tubing would dump heat gathered by solar collectors into the insulated layer of sand in summer, and extract it during the winter. Although sand isn't an ideal material for this type of system, it's cheap and easy to work with.

Bensonwood Is Reinventing the House

Posted on August 3, 2010 by Alex Wilson in Energy Solutions

I had the good fortune last week to spend a few hours touring the Bensonwood offices and factory in Walpole, New Hampshire. I’ve known Tedd Benson for perhaps 20 years, and knew of him a lot longer than that through his writings. He pretty-much created the modern timber-framing profession, starting back in the early 1970s when he set out to reinvent the craft of timber-frame construction that our New England ancestors used centuries ago.

A Custom Builder's First EarthCraft House

Posted on August 3, 2010 by Danny Kelly in Guest Blogs

Having completed an Energy StarLabeling system sponsored by the Environmental Protection Agency and the US Department of Energy for labeling the most energy-efficient products on the market; applies to a wide range of products, from computers and office equipment to refrigerators and air conditioners. house, we wanted to take the next step in our “walk, jog, run” model. We were ready to jog – we decided to enroll a house in one of the many programs that certifies green homes.

By this time, our knowledge had grown, and we felt like we were up to speed on all the new products and techniques of green building. The NAHBNational Association of Home Builders, which awards a Model Green Home Certification. had formalized its Green Building Guidelines; we had read them and attended a brief seminar.

Do All Houses Need Mechanical Ventilation?

Posted on August 2, 2010 by Scott Gibson in Q&A Spotlight

A central aim of energy-efficient building is to eliminate air leaks through the roof and exterior walls. A leaky building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials. not only makes it harder to heat and cool a house but also increases the risk of condensation and moisture damage.

Builders are getting the message about air sealing. But the tighter the house, the greater the need for some type of mechanical ventilation — and that raises construction costs. Is it possible to build a house with just enough air leakage to satisfy fresh air requirements without a ventilation system while still reaping some energy rewards?

Lambs’ Wool Insulation Enters US Market

Posted on August 1, 2010 by Carl Seville, GBA Advisor in Green Building Curmudgeon

I had an interesting meeting recently with a group of gentlemen who plan to distribute lambs’ wool insulation imported from New Zealand. Their company, Lambsulation, is gearing up to distribute throughout the US. They contacted me to get my impressions of their product and how they might effectively market it to the green building community. I know that wool is a good insulator. As a kid at sleep-away camp, I clearly remember having to wear wool sweaters that made my skin itch when camping, so we would stay warm in case we got wet.

Air-Sealing Tapes and Gaskets

Posted on July 30, 2010 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

UPDATED March 8, 2013

After this article was published, Martin Holladay conducted a test of eleven air-sealing tapes on a variety of materials. To read the results of Holladay's testing, see Backyard Tape Test and Return to the Backyard Tape Test.


Posted on July 27, 2010 by Alex Wilson in Energy Solutions

Last week, after reviewing a little physics regarding condensation and latent heat, I described how air conditioners remove unwanted humidity. This week I’ll examine how dehumidifiers work in removing moisture and when it makes sense to use them.

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