The most recent blogs at Green Building Advisor

Basement Insulation — Part 1

Posted on August 29, 2012 by Marc Rosenbaum in Guest Blogs

A common truism (that isn't) is “heat rises.” Actually, what rises is air that is warmer than the surrounding air. Anyone who has lived with a wood stove knows this — it's a lot hotter at the ceiling in the room with the stove than it is at the floor. But heat flows from hot to cold, so it readily goes from our houses down into whatever connection they have with the ground, because the ground is cooler than the temperature most of us like our homes to be at.

Looking Through Windows — Part 2

Posted on August 28, 2012 by Roger Normand in Guest Blogs

[Editor's note: Roger and Lynn Normand are building a Passivhaus in Maine. This is the sixth article in a series that will follow their project from planning through construction.]

Grading the Installation Quality of Insulation

Posted on August 27, 2012 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Six years ago, RESNET published a major revision of the 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. Standards, officially named the 2006 Mortgage Industry National Home Energy Rating Systems Standards. One important new feature in the standards was the grading of insulation installation quality. Before this change, R-13 insulation installed poorly (as shown in the second photo, below) was equivalent to any other R-13 insulation, including insulation with impeccable installation quality (as shown at the top of this article).

On Shutters and Water Management

Posted on August 24, 2012 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

I recently walked through a neighborhood in a Massachusetts town on the South Shore. As you might expect, the homes facing the ocean tended to be more luxurious, while the homes a few blocks in from the beach tended to be more humble.

It’s fun to look at houses from the sidewalk (or, in this case, the beach). During my stroll, I ruminated on house design and construction quality. In this blog, I’ll focus on two themes: the first concerns shutters, and the second concerns flashing and water-management details.

Insulation to Keep Us Warm — Not Warm the Planet

Posted on August 23, 2012 by Alex Wilson in Energy Solutions

I’ve been pretty vocal about a big problem with some of our most common insulation materials: that they are made using blowing agents that are highly potent greenhouse gases.

All extruded polystyrene (XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation.) and most closed-cell spray polyurethane foams (SPF) are made with HFC (hydrofluorocarbon) blowing agents that have global warming potentials (GWPs) many hundreds of times greater than that of carbon dioxide. (My apologies for contaminating this column with so many acronyms!)

Insulation: good news, bad news

Better Video Delivery Mechanism

Posted on August 22, 2012 by Daniel Morrison in Green Building Blog

When we developed GBAGreenBuildingAdvisor.com a few years ago, we knew that we would need, want, and eventually have a deep video program, but because the pile of work to do in order to meet our deadline was pretty darned big, and because we were a bunch of print guys and gals building this thing, we decided to let the video program sit on the back burner. We produced some, but didn't spend the resources to go hog-wild.

Trade Contractor Management — Part 5

Posted on August 22, 2012 by Carl Seville, GBA Advisor in Business Advisor

The most time-intensive part of creating a trade contractor management program is creating your company’s specifications for each trade which, in turn, provide you with the information to include in your checklists. To get started, assemble any and all material you have that includes standard specifications. Plans and spec books from previous jobs, your own subcontracts, trade contractor management books and programs, and your own experience are good places to start.

Looking Through Windows — Part 1

Posted on August 21, 2012 by Roger Normand in Guest Blogs

[Editor's note: Roger and Lynn Normand are building a Passivhaus in Maine. This is the fifth article in a series that will follow their project from planning through construction.]

When we first began looking at windows for our Passivhaus project, we started with a list of 15 window manufacturers. We whittled the list down to two: Schüco, which on paper looked like the best European-style window, and Pella, the best North American style window.

Are Seven Heads Better Than Three?

Posted on August 20, 2012 by Scott Gibson in Q&A Spotlight

John Bell, building a 3300-sq. ft. house in eastern Pennsylvania, is weighing his options for heating and cooling, and it comes down to a conventionally ducted air-source heat pumpHeat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps. or a multi-head ductless minisplit system made by Fujitsu.

Just Two Minisplits Heat and Cool the Whole House

Posted on August 17, 2012 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Carter Scott was one of the first builders bold enough to build a cold-climate home heated by only two ductless minisplit units (one in the downstairs living room, and one in the upstairs hallway). Skeptics predicted that the unheated bedrooms would be cold and uncomfortable. Yet Scott was confident that the home’s excellent thermal envelope — with high-R walls, triple-glazed windows, and low levels of air leakage — would keep the homeowners comfortable even when the bedroom doors were closed.

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