Q&A Spotlight

Are Blower-Door Regulations Too Big a Burden?

Posted on October 10, 2011 by Scott Gibson

Building tight houses is a fundamental step toward energy efficiency, and figuring out how well you’ve done is actually pretty simple.

Air leakage is calculated with a blower-door testTest used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas.. A technician depressurizes the house with a blower sealed into a doorway and measures how much air can pass through the 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..

Does R-Value Trump Thermal Mass?

Posted on October 3, 2011 by Scott Gibson

Jesse Lizer’s plans for a new house in Climate Zone 6 call for a 60-foot long walkout basement wall on the north side. The three below-grade foundation walls will be built with insulated concrete forms (ICFs) with an R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. of roughly R-25.

How to Build Efficiently in Massachusetts

Posted on September 26, 2011 by Scott Gibson

Noah Kaput and his wife seem to be off to a good start in planning their 2,100-sq. ft. house in Massachusetts.

Is the Green Movement Just Spinning Its Wheels?

Posted on September 19, 2011 by Scott Gibson

For GBAGreenBuildingAdvisor.com senior editor Martin Holladay, it all started with a column in The New York Times provocatively titled “Going Green But Getting Nowhere.”

The author, Gernot Wagner, contends that individuals can make no meaningful impact on reducing carbon emissions and staving off global climate change.

Even if each of the 1 billion Catholics on Earth decreased their emissions to zero overnight, Wagner writes, “the planet would surely notice but pollution would still be rising.”

Is Green Building for Everyone?

Posted on September 12, 2011 by Scott Gibson

Is green building too narrow in focus, suitable only for people who keep the windows closed and let mechanical systems regulate temperature and humidity? What about people who like fresh air, even in winter, and are looking for minimal intervention from mechanical heating and cooling equipment?

That seems to be at the heart of a question from Maria Hars, a GBAGreenBuildingAdvisor.com reader who lives in a passive solar house built 30 years ago in northern Massachusetts.

The Pros and Cons of Running a Dehumidifier

Posted on September 6, 2011 by Scott Gibson

Superinsulation is the most effective weapon we have against wintertime heat losses. R-values of 60 or more in the roof and 40 in exterior walls can slow the movement of heat to a crawl, keeping energy costs far below what they’d be in a conventionally built house.

Yet Harry Seidel puts his finger on a potential problem. During the summer, any heat generated inside the house will have just as much trouble getting out of the house.

Are LEDs Worth Their Extra Cost?

Posted on August 29, 2011 by Scott Gibson

Standard incandescent light bulbs are among the most profligate energy consumers available, turning more than 90% of the energy they consume into heat rather than light. These old-school bulbs are inexpensive and cast a pleasingly warm light, but their days are numbered.

Compact fluorescent lamps (CFLs) are gradually taking their place. Although they’re more expensive, the cost is coming down and dimmable versions have become available. Bulb life is much longer and, more important, CFLs deliver much more light per watt of electricity than incandescent bulbs.

Planning a New Home: Where to Spend the Money?

Posted on August 22, 2011 by Scott Gibson

A tight, well-insulated 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. is fundamental to a high-performance house. So is a heating and cooling system that keeps it comfortable with a minimum input of energy. What happens when the construction budget can’t handle the added costs of high-quality windows and extra insulation as well as high-efficiency mechanicals?

That basic question is what’s plaguing Dave W as he works to complete plans for his new home.

Choosing a High-Performance Wall Assembly

Posted on August 18, 2011 by Scott Gibson

Jesse Lizer’s new house will be in Climate Zone 6, where he can expect 7,400 heating degree days a year. High R-values in the 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. are a high priority.

How to Insulate a Foundation

Posted on August 8, 2011 by Scott Gibson

Peter Fusaro is building a high-efficiency house on spec, and his plans include insulating the foundation walls. The question is how.

One option is to apply rigid foam to the outside of the foundation. That would leave roughly 1 ft. of insulation above grade, and Fusaro is concerned about how durable the foam would be.

Another possibility is to use a sandwich of 2 in. of foam between two outer faces of concrete, each 4 in. thick, making an assembly with both structural and thermal properties. He’s been told a wall built that way would have an effective R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. of 19.27.

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