The most recent blogs at Green Building Advisor

Fundamentals of Psychrometrics, Part 1

Posted on May 27, 2015 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

I have a confession to make: I've fallen in love with psychrometrics! After water itself, moist air has got to be the most interesting substance in building science. And the psychrometric chart, in all its many manifestations and with its multitudinous quantities, is a thing of beauty. Well, at least it is to me, and maybe it will be to you, too, after you get to know it a bit better.

Get Ready for a New Energy Code

Posted on May 26, 2015 by Stuart Kaplow in Guest Blogs

The 2015 version of the International Energy Conservation Code is soon to be upon you.

Modern building codes are most often adopted by local government legislative bodies and as such vary from place to place. The IECC International Energy Conservation Code. is in use or adopted in 47 states, the District of Columbia, the U.S. Virgin Islands, New York City, and Puerto Rico.

Does This Roof Need a Vapor Retarder?

Posted on May 25, 2015 by Scott Gibson in Q&A Spotlight

David Amenhauser is buying a home near Boston, Massachusetts, that's apparently still under construction, but far enough along to have the roof framed and insulated.

How to Hang Airtight Drywall

Posted on May 25, 2015 by Myron Ferguson in Green Building Blog

Stopping air leaks is the single most important part of making a house more energy efficient. You can stop air on the outside with plywood, housewrap, and tape, but the best 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. is a system that incorporates the whole wall or roof assembly.

Sub-Slab Mineral Wool

Posted on May 22, 2015 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Most green builders who need a layer of horizontal insulation under a concrete slab specify expanded polystyrene (EPSExpanded polystyrene. Type of rigid foam insulation that, unlike extruded polystyrene (XPS), does not contain ozone-depleting HCFCs. EPS frequently has a high recycled content. Its vapor permeability is higher and its R-value lower than XPS insulation. EPS insulation is classified by type: Type I is lowest in density and strength and Type X is highest.), an affordable product that performs well in this application. If a builder specifies high-density EPS rated for below-grade use, the product is very durable.

That said, many green builders don’t like EPS. Some object to the fact that polystyrene is made from petroleum, while others worry about possible health problems associated with the brominated flame retardants that polystyrene manufacturers add to EPS.

Prepping for Spray Foam

Posted on May 21, 2015 by Michael Chandler, GBA Advisor in Green Building Blog

Spray-foam insulation is gaining popularity these days, and for good reason. Not only does it offer lots of R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. per inch, but it also air-seals the house. I’ve been building custom homes in North Carolina for more than 20 years, and I’ve been using spray-foam insulation for the past four. These days, all my projects get 8 in. to 12 in. of foam under the roof deck, and I often use foam to insulate walls and crawlspaces as well.

Does the Nest Thermostat Save Energy?

Posted on May 20, 2015 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

The Nest Learning Thermostat has been on the market for nearly four years now. One of the biggest things the Nest folks use as a selling point is energy savings. "Programs itself. Then pays for itself." That's the first thing you see when you go to the Nest homepage. But what do the data say? Three independent studies plus a white paper from Nest provide some answers. (GBAGreenBuildingAdvisor.com first reported on these three studies in a February 2015 news story.)

Nine Surprising Signs That Momentum Is Building for Climate Action

Posted on May 19, 2015 by Seth Shulman in Guest Blogs

A spate of recent developments suggests momentum is building to address climate change — including some truly unexpected and inspiring signs in the United States and around the world.

Of course, huge obstacles remain: Florida Governor Rick Scott would allegedly like to censor any official mention of the subject. Oklahoma Senator Jim Inhofe still seems to think that carrying a snowball onto the floor of the Senate offers some kind of "evidence" that global warming is hoax.

Smart Scheduling Helps Projects to Finish on Time

Posted on May 19, 2015 by Michael Patterson in Green Building Blog

It’s been said that stereotypes are stereotypes because they contain a grain of truth. While “two weeks” may be funny, it hits close enough to home that whatever smile we contractors may have is a bit pinched, and whatever smiles our clients may have are knowing ones. I’m all for smiles, but I’d rather they be the satisfied grins of contractors and homeowners whose jobs went according to plan. Scheduling a project well ensures that satisfied grins are the rule.

Is Passivhaus Right for a Cold Canadian Climate?

Posted on May 18, 2015 by Kent Earle in Guest Blogs

This is something I’ve been wrestling with since we decided on building a superinsulated, highly energy efficient home. And really this is something that I think a lot of builders, architects, and designers of eco- and green homes have been debating since the PassivhausA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. concept came to North America in the past few years.

Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!