Musings of an Energy Nerd

High-Solar-Gain Glazing

Posted on July 31, 2009 by Martin Holladay

Homeowners can now receive a federal tax credit for 30% of the cost of new energy-efficient windows. The credit was authorized by the American Recovery and Reinvestment Act (ARRA) signed by President Obama in February.

Green Homes Don’t Have To Be Durable

Posted on July 24, 2009 by Martin Holladay

According to most green advocates, green buildings must be durable. Alex Wilson memorably summed up the case for durability in an Environmental Building News article titled “Durability: A Key Component of Green Building.”

In Defense of the Lawn

In Defense of the Lawn

Posted on July 15, 2009 by Martin Holladay

Environmentalists often bad-mouth lawns. The anti-lawn stance was summed up in a recent essay by Kerry Trueman, who wrote, “The typical American lawn is pretty much an unmitigated environmental disaster.”

Installing Fiberglass Batts Right

Installing Fiberglass Right

Posted on July 10, 2009 by Martin Holladay

Of all of the commonly used types of insulation — including cellulose, rigid foam, and spray polyurethane foam — fiberglass batts perform the worst. As typically installed, fiberglass batts do little to reduce airflow through a wall or ceiling assembly; rarely fill the entire cavity in which they are installed; and sometimes permit the development of convective loops that degrade insulation performance.

Knowing this, why would any builder choose to install fiberglass batts? The answer is simple: because fiberglass batts cost less than any other type of insulation.

Residential energy use keeps growing

Getting More Efficient, But Using More Energy

Posted on June 29, 2009 by Martin Holladay

Back in the 1970s, energy activists promoted conservation. The attractiveness of conservation waned, however, as Americans began to associate the word with sacrifice. Public relations experts responded by promoting something sexier than conservation: energy efficiency.

Plug load problem 2

Tackling the Plug Load Problem

Posted on June 18, 2009 by Martin Holladay

The biggest energy load in most houses is space heating. When it comes to electricity, the list of major loads usually includes air conditioners, water heaters, and lighting.

Almost all other residential electrical loads are usually categorized as “plug loads.” According to a paper by Sam Rashkin, Glenn Chinery, and David Meisegeier, “plug loads are the fastest growing energy load in the residential sector.”

Designing a Good Ventilation System

Posted on June 15, 2009 by Martin Holladay

UPDATED on April 15, 2016

Most green builders include some type of mechanical ventilation system in every home they build. That’s good. Since green buildings usually have very low levels of air leakage, mechanical ventilation is usually essential.

Unfortunately, several research studies have shown that a high number of mechanical ventilation systems are poorly designed or installed.

Farewell to the Chimney?

Posted on June 6, 2009 by Martin Holladay

For thousands of years, the chimney has been closely associated with our concept of home. Upon spying smoke curling from a distant chimney, the weary traveler ends his journey with lightened steps.

When I built my house in Vermont, as a much younger man than I am today, I designed a house with two chimneys. The house has a cellar, first floor, second floor, and attic; because I wanted the chimneys to rise five feet above the ridge, they had to be 40 feet tall.

Passivhaus Standard for Superinsulated Houses

Passivhaus For Beginners

Posted on May 27, 2009 by Martin Holladay

UPDATED on April 16, 2015

More and more designers of high-performance homes are buzzing about a superinsulation standard developed in Germany, the 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. standard. The standard has been promoted for almost two decades by the Passivhaus Institut, a private research and consulting center in Darmstadt, Germany.

Do PV Systems Make Sense?

Thinking About Net Zero Energy

Posted on May 19, 2009 by Martin Holladay

UPDATED March 28, 2013

The average new home is so poorly built, it’s enough to make an environmentalist weep.

Windows are routinely installed without any consideration of orientation. As a result, south windows fail to take full advantage of free solar heat during the winter, while west windows worsen summer overheating. Windows are often installed in unshaded walls, even in hot climates. In the absence of legal requirements for high-performance windows, builders regularly choose windows with appalling U-factors and solar heat gainIncrease in the amount of heat in a space, including heat transferred from outside (in the form of solar radiation) and heat generated within by people, lights, mechanical systems, and other sources. See heat loss. coefficients (SHGCs).

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