Musings of an Energy Nerd

Brick Buildings Need Roof Overhangs

Posted on September 23, 2014 by Martin Holladay, GBA Advisor

I'm in Portland, Maine, for the 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. Network conference. Yesterday morning I walked a few blocks from my hotel to the conference site, through downtown Portland.

The old commercial district here has lots of handsome old three-story and four-story brick buildings. I love to look at the details on these older buildings. At first glance, it may appear that architectural ornament has been randomly applied to these façades; but if one pays attention, it soon becomes clear that most of these façade elements have a function.

New Books on Green Building

Posted on September 19, 2014 by Martin Holladay, GBA Advisor

If you are a cold-climate architect looking for a reference book that provides guidance on designing energy-efficient superinsulated buildings, I strongly suggest that you buy William Maclay’s The New Net ZeroProducing 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. Calculating net-zero energy can be difficult, particularly in grid-tied renewable energy systems, because of transmission losses in power lines and other considerations.. It’s the best book on the topic by far.

All About Attics

Posted on September 12, 2014 by Martin Holladay, GBA Advisor

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.

All About Microwave Ovens

Posted on September 5, 2014 by Martin Holladay, GBA Advisor

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.

Get Ready for Smart Appliances

Posted on August 29, 2014 by Martin Holladay, GBA Advisor

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.

Geothermal Energy and Narrow Streets

Posted on August 22, 2014 by Martin Holladay, GBA Advisor

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.

Bathroom Exhaust Fans

Posted on August 7, 2014 by Martin Holladay, GBA Advisor

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.

A Canadian Editor Questions Passivhaus Dogma

Posted on August 1, 2014 by Martin Holladay, GBA Advisor

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.

What Should I Do With My Old Windows?

Posted on July 25, 2014 by Martin Holladay, GBA Advisor

If you’re trying to lower your energy bills, you have probably plugged many of your home’s air leaks and have added insulation to your attic floor. Now you may be wondering, “What should we do about our old windows?”

Unfortunately, there is no clear answer to this question. Sometimes it makes sense to leave old windows exactly the way they are. Sometimes it makes sense to repair the windows’ weatherstripping and add storm windows. And sometimes it makes sense to replace old windows with new energy-efficient windows.

The 2012 Code Encourages Risky Wall Strategies

Posted on July 18, 2014 by Martin Holladay, GBA Advisor

Builders who follow the prescriptive requirements of the 2012 International Residential Code (IRCInternational Residential Code. The one- and two-family dwelling model building code copyrighted by the International Code Council. The IRC is meant to be a stand-alone code compatible with the three national building codes—the Building Officials and Code Administrators (BOCA) National code, the Southern Building Code Congress International (SBCCI) code and the International Conference of Building Officials (ICBO) code.) in Climate Zone 6, 7, or 8 are required to install a minimum of “20+5 or 13+10” wall insulation. What does this mean? According to an explanatory footnote in the code, the “First value is cavity insulation, [and the] second is continuous insulation or insulated siding, so ‘13+5’ means R-13 cavity insulation plus R-5 continuous insulation or insulated siding.”

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