The most recent blogs at Green Building Advisor

Summer is Pretty Boring in a Superinsulated House

Posted on August 14, 2014 by Erik Haugsjaa in Guest Blogs

Summers in Massachusetts are easy in comparison to winters. Some people (myself included — a bit) saw air conditioning as the devil or something.

Using the Pen Test for Control Layers

Posted on August 13, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

I listened to the IAQ Radio podcast a few weeks ago when they interviewed Lew Harriman and Terry Brennan, who were discussing the new moisture control guide published by the EPA last year. Brennan is the lead author of the document, and it's a really great resource full of useful information about indoor air quality, fundamental building science principles, and how to control moisture.

The Potwine Passivhaus in Amherst

Posted on August 12, 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. In this first blog in a planned series, Arango reports on the start of their project.

Why Is My House So Hot?

Posted on August 11, 2014 by Scott Gibson in Q&A Spotlight

When Jeff Watson realized that the insulation on his attic floor was rated at R-11, he did what any energy professional would have suggested: he added more insulation. He air sealed the attic floor, added ventilation baffles where necessary, and blew in a thick layer of R-60 insulation. But he isn't entirely satisfied at the results.

"As expected, the temperature in the house doesn't fluctuate as much," Watson writes in a Q&A post at GreenBuildingAdvisor. "However, I feel as if I'm using AC more.

Bathroom Exhaust Fans

Posted on August 7, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Older homes often lack bathroom exhaust fans. In the old days, if the bathroom was smelly or steamy, you were supposed to open a window to air it out.

This isn’t a very logical ventilation method, especially when temperatures are below zero, or when the weather is 90°F and humid. Yet this time-honored method of bathroom ventilation is still enshrined in our building codes. According to the 2009 International Residential Code (sections R303.3 and M1507.3), a bathroom with an operable window does not need to have a bath exhaust fan.

The Achilles’ Heel of Zoned Duct Systems

Posted on August 6, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Last week I wrote about what happens when you try to save energy by closing air conditioning registers in unused rooms. In the end, I recommended not doing it because you won’t save money and you may create some big problems for yourself, like freezing up the coil and killing your compressor.

At the end of the article, I mentioned that zoned duct systems do close off registers, and that doing so can be OK with the right kind of equipment and design. But there’s one thing often done in zoned duct systems that’s rarely done well.

Choosing Kitchen Appliances for a Passivhaus

Posted on August 5, 2014 by Andrea Lemon in Guest Blogs

After living in our house for 1½ years, I finally have enough distance to evaluate the many decisions that went into building it. I plan to write a series of "Hindsight" posts, speaking frankly about what worked and what we'd do differently if we had to do it all over again.

To start the series, I'm going to keep it simple and talk about our kitchen appliances. Don't worry, I'll cover all the hairy Passivhaus details eventually, but I'll start at the shallow end.

Running Our House on Prius Power

Posted on August 4, 2014 by Paul Honig in Guest Blogs

On Sunday morning June 30th, we experienced our first prolonged power outage since moving in to our new passive house in Connecticut. A tree came down on one of the power lines around the corner and power was out for about six hours. It was time to see our inverterDevice for converting direct-current (DC) electricity into the alternating-current (AC) form required for most home uses; necessary if home-generated electricity is to be fed into the electric grid through net-metering arrangements. in action — the inverter that we bought from Converdant Vehicles to turn our Prius into a backup generator.

A Canadian Editor Questions Passivhaus Dogma

Posted on August 1, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Today's brief blog — a departure from my usual practice of writing in-depth articles — was inspired by a recent editorial by Richard Kadulski, the editor of a Canadian newsletter called Solplan Review.

Is It OK to Close Air Conditioner Vents in Unused Rooms?

Posted on July 30, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Your air conditioner, 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., or furnace probably uses a lot of energy. Heating and cooling makes up about half of the total energy use in a typical house. For air conditioners and heat pumps using electricity generated in fossil-fuel fired power plants, the amount you use at home may be only a third of the total.

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