The most recent blogs at Green Building Advisor

How to Tell If Your Air Conditioner Is Oversized

Posted on September 3, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Back in 2009, I had a new air conditioner installed our condo. The previous one was an ancient 25 years old and barely limping along. It wasn't cooling much, and the summer electric bills had risen.

Cold Weather Slows Progress at the Potwine Passivhaus

Posted on September 2, 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 second blog in a planned series.

Overheating from South Windows

Posted on September 1, 2014 by Ted Lemon in Guest Blogs

For the past two years, Ted Lemon and Andrea Lemon have been living in 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. which they built in Brattleboro, Vermont. Ted Lemon wrote the essay below in July 2012.

Get Ready for Smart Appliances

Posted on August 29, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Utility executives and some energy-efficiency experts have been dreaming for years of a smart electricity grid connected to smart appliances that can be remotely controlled. In many North American cities, however, the installation of smart meters has faced strong opposition from some homeowners. The resulting fallout has amounted to a public relations nightmare for electric utilities.

Origami-Inspired Homes

Posted on August 28, 2014 by Greg Labbe in Guest Blogs

There’s a reason that every high-performance car is sleek and compact in shape; sleekness improves performance. The same principle applies to centuries-old sculptures that keep their features and endure centuries of weathering and the test of time: keep the shape simple.

Unfortunately, the current trend is to build large homes that have poorly designed floor spaces. The physical shape of these origami-like buildings impacts our lives, our comfort, and our energy bills.

Is Oriented Strand Board as Impermeable as They Say?

Posted on August 27, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Oriented strand board (OSB) gets blamed for a lot of problems that are really the fault of the designers and builders. Part of the problem, of course, is the perrenial confusion between correlation and causality. OSB hit the market as we really started getting serious about insulation and air sealing.

Which Building Energy Statistics Make the Most Sense?

Posted on August 26, 2014 by Bill Maclay in Guest Blogs

There are many measures used to evaluate building energy efficiency: total kBtu1,000 Btus, kBtu/sq. ft./year, kWh/year, therms/year, kWh/sq. m./year, $/year, kBtu/person — and more. But determining when to use which metric, and even more importantly, how to make sense of a comparison of the energy efficiency of two different buildings, is no easy task.

What’s More Important, Air-Sealing or Insulation?

Posted on August 25, 2014 by Scott Gibson in Q&A Spotlight

Green Building Advisor reader Ani Brown is getting ready to build a new house, and like most people in her position Brown will have to make some important choices on how to make the most of a limited construction budget.

Her immediate concern is insulation and air-sealing, two related details that will have a lot to do with how comfortable and durable the new house will be.

Geothermal Energy and Narrow Streets

Posted on August 22, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Everybody seems to love geothermal energyHot water or steam extracted from reservoirs beneath the Earth's surface; can be used for heat pumps, water heating, or electricity generation. The term may also mean the use of near-constant underground temperatures by ground-source heat pumps to provide heating and cooling.. That's why many American homeowners brag that they heat their house with renewable energy, saying, “I've got a geothermal system that extracts heat from the soil in my backyard.”

Well, I'm sorry to disappoint you, but you've been misinformed. You don't have a geothermal system. All you have is a heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump. that runs on electricity.

Just because the heat-pump salesman told you that it’s a geothermal system, doesn't mean it is.

The Passive House Conference in California Is Where It’s At!

Posted on August 20, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

The 9th annual North American 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. Conference is less than a month away. You knew it's going to be in California, right?

It's unfortunate that the other Passivhaus group has chosen to use the same name that the Passive House Institute U.S. (PHIUS) has been using since 2006, but I've already discussed that confusion. (Full disclosure: I am on the board of directors of PHIUS.)

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