Musings of an Energy Nerd

Building Houses and Saving Energy in Nicaragua

Posted on April 26, 2010 by Martin Holladay

There's a reason this week's blog is late: I just returned from a week in Nicaragua.

I'm posting a few photos from Central America. My next blog should appear on schedule at the end of the week.

A ‘Magic Box’ For Your Passivhaus

Posted on April 16, 2010 by Martin Holladay

UPDATED on March 13, 2015

By designing a tight envelope with thick insulation, 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. designers work hard to whittle a home’s space heating loadRate at which heat must be added to a space to maintain a desired temperature. See cooling load. to a bare minimum. Many European designers strive to get the heating load so low that all space heat can be provided by raising the temperature of the ventilation air.

Airtight Wall and Roof Sheathing

Posted on April 9, 2010 by Martin Holladay

UPDATED on March 8, 2016

In the early 1970s, residential builders knew almost nothing about air tightness. The first residential air barriers were installed in Saskatchewan in the late 1970s, when pioneering Canadian builders began sealing the seams of interior polyethylene sheeting with Tremco acoustical sealant. The Canadian builders (and their American imitators) went to a lot of trouble to weave the interior poly around framing members at rim-joist areas and partition intersections.

Researchers Predict U.S. Furnace Industry Is Doomed

Posted on April 1, 2010 by Martin Holladay

OAK RIDGE, TENN., April 1 — According to Andrei Constantinescu, a senior researcher at Oak Ridge National Laboratory, it won’t be long before new American homes no longer require central heating. “Every year, the heat produced by electronic gadgets is increasing,” explained Constantinescu. “By 2014, most new American homes won’t need a furnace.”

As televisions get larger, their heat output increases. “Four plasma TVs can heat a house in Kentucky,” said Constantinescu. “If you throw in a set-top box and two or three computers, you should be fine as far north as Maine.”

Choosing Triple-Glazed Windows

Posted on March 26, 2010 by Martin Holladay

Since 1977, when Sweden introduced its stringent energy code, almost all new homes in Sweden have been equipped with triple-glazed windows. Here in the U.S., where energy codes are more lax, triple-glazed windows are still rare.

For a minority of U.S. builders, however — especially cold-climate builders of superinsulated homes — triple-glazed windows are considered essential. Since few U.S. manufacturers offer high-solar-gain triple-glazed windows, most Americans get these windows from Canadian manufacturers.

Forget Vapor Diffusion — Stop the Air Leaks!

Posted on March 19, 2010 by Martin Holladay

Last week’s blog answered some common questions about vapor retarders. This elicited a comment from Bill Rose, research director of the Building Research Laboratory at the University of Illinois in Champaign. “We might imagine a future in which the building code sections that address the vapor barrier would all go blank,” Rose wrote.

Vapor Retarders and Vapor Barriers

Posted on March 12, 2010 by Martin Holladay

UPDATED on May 15, 2015

Although building science has evolved rapidly over the last 40 years, one theme has remained constant: builders are still confused about vapor barriers.

Any energy expert who fields questions from builders will tell you that, year after year, the same questions keep coming up: Does this wall need a vapor barrier? Will foam sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. trap moisture in my wall? How do I convince my local building inspector that my walls don’t need interior poly?

The Energy-Efficiency Pyramid

Posted on March 5, 2010 by Martin Holladay

UPDATED on September 24, 2013

We’re all familiar with the food pyramid — the triangle with grains and cereals at the bottom and fats and sugars at the top. Inspired by the food pyramid, a Midwestern electric utility, Minnesota Power, has created a useful graphic called the energy conservation pyramid. (According to a Minnesota Power spokesperson, the originator of the conservation pyramid was Bob McLean, the chief operating officer at Hunt Utilities Group.)

Air Conditioner Basics

Posted on February 26, 2010 by Martin Holladay

What does a Vermonter know about air conditioning? I live so close to the Canadian border that half of the radio stations are in French. If my house needs cooling, I just let the fire in the wood stove die down.

When I first began reporting on air conditioning topics over a decade ago, I felt out of my element. Impelled by the certainty that there’s no such thing as a dumb question, I’ve managed over the years to badger a few air-conditioner experts, all of whom contributed to my education. So now I finally know the difference between an evaporator coil and a condenser coil.

Duct Leakage Testing

Posted on February 19, 2010 by Martin Holladay

For years, Americans who would never put up with leaky plumbing pipes have been willing to accept leaky ducts. While water damage is hard to ignore, the damage caused by leaky ducts is more subtle. Yet leaky ducts not only waste huge amounts of energy — they can also lead to comfort complaints, moisture problems, mold, and rot.

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