The most recent blogs at Green Building Advisor

Solar Energy Can Make the Grid More Resilient

Posted on December 5, 2013 by Alex Wilson in Energy Solutions

In my blog last week, I reported on The Navy Yard in Philadelphia, a remarkable 1,200-acre business campus with 300 companies employing 10,000 people — with as many as 35,000 employees projected eventually. What had attracted me to the facility while I was in town for a conference, was an innovative demonstration that’s been launched showing how solar-electric (photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow.) systems with battery back-up and smart controls can help to create a more resilient power grid.

How to Get Your Ducts Inside the Building Enclosure

Posted on December 4, 2013 by Allison A. Bailes III, PhD in Building Science

I'm a big advocate of getting ducts inside the building enclosure. In cooling climates, getting ducts out of an unconditioned attic can save you 15% on your electricity bills. It can reduce the size of air conditioner you need by 25%. If it's not in such a harsh environment, your air conditioner will last longer, too.

Green Buildings, Missed Opportunities, and Lessons Learned

Posted on December 3, 2013 by Rachel White in Guest Blogs

I once gave a talk at a Build Boston conference with Jonathan Kantar of Sage Builders, on the topic “Green That Means Something.” Yes — the implied subtext is that there’s a whole lot of “green” out there that doesn’t mean all that much. But if you visit regularly, you probably already knew that.

Insulating the Roof of a Bonus Room

Posted on December 2, 2013 by Scott Gibson in Q&A Spotlight

Andrew K has a project that should ring a bell with lots of homeowners: What's the best way of insulating a room over the garage so it becomes useful, conditioned spaceInsulated, air-sealed part of a building that is actively heated and/or cooled for occupant comfort. ?

Andrew lives in Massachusetts, in Climate Zone 5A, and would like to turn the space, what real estate agents used to call a "bonus room," into an office. The roof is framed with 2x8 rafters and already has both soffit and ridge vents, but no insulation whatsoever.

The Klingenberg Wall

Posted on November 29, 2013 by Martin Holladay in Musings of an Energy Nerd

When Katrin Klingenberg designed the first single-family Passivhaus in the U.S. in 2003, she used 12-inch-deep I-joists (TJIs) as wall studs. Located in Urbana, Illinois, the house was sheathed on the exterior side of the vertical I-joists with vapor-permeable fiberboard and on the interior with OSB, which acted as an interior 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 interior vapor retarder, and structural bracing. The bays of the engineered studs were filled with blown-in fiberglass insulation.

The Philadelphia Navy Yard is Repurposed

Posted on November 28, 2013 by Alex Wilson in Energy Solutions

I’m just back from Philadelphia, where I spent most of last week at GreenBuild, the nation’s premier conference and expo focused on the burgeoning green building movement. I heard there were 25,000 attendees.

Several of us from BuildingGreen drove down the day before the conference started, and Brent, Candace, and I didn’t have any commitments on Tuesday afternoon, affording us the opportunity to visit The Navy Yard, which I had been hearing a lot about.

The History of Peeling Paint, Insulation, and Vapor Barriers

Posted on November 27, 2013 by Allison A. Bailes III, PhD in Building Science

Back in the 1930s, a rash of paint-peeling showed up across North America. One thing that most of these homes had in common was insulation in the walls. Painters put two and two together and decided that the problem was the insulation. According to building scientist Bill Rose, the painters surmised that the problem was happening because insulation “draws water,” and some refused to paint insulated houses.

Point-of-Use Electric Tankless Water Heaters

Posted on November 26, 2013 by Rick DuRapau in Guest Blogs

A couple of years ago, I was standing at my kitchen sink, idly waiting the minute or so for hot water, noticing my poor parched backyard. Central Texas was (and still is) in the death grip of a prolonged, severe drought. Our lakes are in really bad shape, and we are under very tight water restrictions.

Then suddenly, I had a mini epiphany: I’m wasting a lot of valuable water while I wait for hot water.

Recent Changes to LEED for Homes — Part 2

Posted on November 25, 2013 by Ann Edminster in Guest Blogs

In this concluding part of my two-part blog series on the soon-to-be-released LEED for HomesLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. version 4, I follow up my introduction to the topic (Part 1), in which I covered some major structural makeovers from LEED for Homes 2008. In that blog, I also discussed changes in just two categories: Water Efficiency (WE) and Indoor Environmental Quality (EQ). On balance, I found those two categories to be most improved … not that I didn’t have some critiques!

Cut-and-Cobble Insulation

Posted on November 22, 2013 by Martin Holladay in Musings of an Energy Nerd

Here at, readers regularly ask about the best way to install rigid foam insulation between studs or rafters. A typical question might go like this: “I’d like to insulate between my studs with strips of 2-inch-thick polyisoPolyisocyanurate foam is usually sold with aluminum foil facings. With an R-value of 6 to 6.5 per inch, it is the best insulator and most expensive of the three types of rigid foam. Foil-faced polyisocyanurate is almost impermeable to water vapor; a 1-in.-thick foil-faced board has a permeance of 0.05 perm. While polyisocyanurate was formerly manufactured using HCFCs as blowing agents, U.S. manufacturers have now switched to pentane. Pentane does not damage the earth’s ozone layer, although it may contribute to smog. . I plan to cut the rigid foam pieces a little bit loose, and seal the edges of the polyiso with canned spray foam. Will this work?”

Register for a free account and join the conversation

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