The most recent blogs at Green Building Advisor

Five Different High-R Walls

Posted on September 18, 2014 by Sam Hagerman in Guest Blogs

Our construction company, Hammer & Hand, has built several wood-framed Passive HouseA 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. buildings in the Pacific Northwest. Over the years, our approach to building high-R walls has evolved.

Study Finds Huge Variation in California HERS Rating Results

Posted on September 17, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

A home energy rating is supposed to tell you how energy-efficient your home is. A certified home energy rater goes to the home and collects all the data relevant to energy consumption in the home (well, all the data included in the rating anyway, which is almost everything).

Housewrap Tape Problems

Posted on September 16, 2014 by Jeff Hoch in Guest Blogs

Every year we inspect thousands of homes with one brand or another of housewrap installed as the water-resistive barrierSometimes also called the weather-resistive barrier, this layer of any wall assembly is the material interior to the wall cladding that forms a secondary drainage plane for liquid water that makes it past the cladding. This layer can be building paper, housewrap, or even a fluid-applied material. (WRB).

As energy costs increase and energy code requirements become more stringent, we are seeing housewrap installations where the seams are sealed with tape. Many housewrap manufacturers have proprietary seam seal tapes that they sell for exclusive use with their housewrap system.

An Insulated Cathedral Ceiling for a European Passivhaus

Posted on September 15, 2014 by Bill Butcher in Guest Blogs

Editor's note: The author, Bill Butcher, is a Certified Passive HouseA 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. Consultant who was project leader on the Denby Dale Passivhaus and is currently leading the Golcar Passivhaus project, a 2,700-square foot three-bedroom house in Golcar, West Yorkshire, England. Some of the technical and construction-related terms used in Bill's essay have been translated from British English to American English.

All About Attics

Posted on September 12, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Most six-year-olds can draw a house. The typical child’s depiction of a house shows a rectangular building with a door and a few windows, topped by a gable roof.

This type of house is fairly common in most areas of the U.S. If the house was built 100 or more years ago, it usually had a cellar or basement underneath the first floor and an attic above the top floor.

Placing Concrete for a Passivhaus Foundation

Posted on September 11, 2014 by Alexi Arango in Guest Blogs

As they set out to build a single-family 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. on Potwine Lane in Amherst, Massachusetts, Alexi Arango and LeeAnn Kim asked themselves, “Is it possible to live without burning fossil fuels?” One measure of success would be meeting their goal of net-zero energyProducing as much energy on an annual basis as one consumes on site, usually with renewable energy sources such as photovoltaics or small-scale wind turbines. performance. This is the third blog in a planned series.

How Your Thermostat Can Grow Mold and Make You Uncomfortable

Posted on September 10, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

I've been experimenting with my family lately. Or is it, experimenting on my family? In either case, I've got the data to confirm something I wrote in a 2011 article.

But before I tell you what I did, first let me show you what happened. In the graph at right, you can see Exhibit A: a moisture mystery. What do you think happened to cause the humidity (blue data) in the air in our condo to rise like that?

Pastiche Architecture

Posted on September 9, 2014 by Greg Labbe in Guest Blogs

Drive out to any of the bedroom communities outside the greater Toronto area and you’re likely to stumble on huge, clunky homes that are so complex in shape that their energy performance is degraded. These homes include uncomfortable rooms, are often challenged by ice dams, and require higher expenditures for maintenance.

Having no more usable space than much smaller (but better designed) houses, these large homes squander conditioned floor space with ostentatious frills. Buying more is really less.

Coping With a Wrong-Sized AC System

Posted on September 8, 2014 by Scott Gibson in Q&A Spotlight

Florida is not the kind of place where you'd want to be without air conditioning for very long, so when Chris Marriner's old system died last spring, he didn't waste much time in replacing it. But what should have been a ticket to indoor comfort hasn't exactly worked out that way.

Marriner's HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. technician decided to replace the 4-ton system with one of the same capacity, even though Marriner knew that because of improvements to 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. the new system probably would be oversized for the 2200-square-foot home. The tech told Marriner the system could be "tuned."

All About Microwave Ovens

Posted on September 5, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

A microwave oven uses less energy than a conventional oven. Even though this statement is broadly true, a microwave oven isn’t always the most efficient way to cook.

So what appliance should you use to heat up or cook your dinner: A gas stovetop? An electric-resistance stovetop? An induction stovetop? A gas oven? An electric oven? A countertop toaster oven? A crockpot? Or a microwave oven?

If all you care about is energy efficiency, it’s possible to come up with an answer to this question — but the answer will depend on the quantity and the type of food you are cooking.

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