Musings of an Energy Nerd

Conventional wood-framed walls perform many functions. Exterior walls are supposed to support the roof load, resist racking, and provide insulation. They must also provide space for routing electrical cables and (in some cases) plumbing pipes or even ductwork. If the walls are built properly, they should also include an air barrierBuilding assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the interior of the assembly, or both..

UPDATED February 27, 2012

Why is it that trivial news stories (for example, reports on Kate Middleton’s wedding dress) often receive disproportionate coverage, while important news stories are sometimes neglected?

Here’s my vote for the most neglected news story of 2011: the radioactive contamination of hundreds of square miles of land around the Fukushima-Daiichi nuclear plant in Japan. Although most news outlets have reported some details of this story, I think it deserves much more attention than it has received.

Energy auditors and insulation contractors have been using infrared cameras to diagnose home-performance problems for over 30 years. Without opening up your walls or ceilings for inspection, a trained specialist can use one of these cameras to locate insulation voids, air leaks, moisture intrusion, thermal bypasses, and thermal bridges. It’s even possible to use an infrared camera to locate leaks in hydronic tubing embedded in a slab.

As the sun sets on 2011 and we all turn our eyes to 2012, it’s time for journalists and consultants to publish their predictions for the coming year. I was briefly tempted to create such a list — something along the lines of “energy prices will be higher, the planet will be warmer, and many regions will be affected by drought” — until I remembered that I’ve always been bad at predicting.

For example, back in the late 1970s, I was convinced that energy prices would rise steeply during the 1980s. I was wrong.

If you are considering investing in an energy-efficiency improvement for your home — for example, additional attic insulation or a photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. system — you probably expect the investment will lower your energy bills. So it’s only natural to ask, “Is this a good investment?”

For example, let’s say that you are considering spending $5,000 on an improvement that will save you $350 a year on your energy bills. Does the investment make economic sense? The answer, of course, is “it depends.”

Act 1, scene 1. An empty lot near Scotland Drive.

Thunder and lightning. Enter three sisters, all RESNET-certified.

First rater:
When shall we three meet again,
In thunder, lightning, or in rain?

Second rater:
When the drywall work is done,
When the zoning battle’s won.

Although I usually only publish one blog a week, I can’t resist posting a rare Saturday blog to rail against bad advice to homeowners from the Federal government and a national green building organization.

Lots of things can go wrong with roofs: bad flashing can cause leaks, a poorly designed valley can turn into a slow-moving glacier, and misplaced gutters can do more harm than good. Experienced roofers see a lot of stupid roofs.

Two new books that might interest green builders recently caught my eye: The BuildingGreen Guide to Insulation Products and Practices by Alex Wilson and The JLC Guide to Energy Efficiency by the editors of The Journal of Light Construction.

Full disclosure: I was a minor participant in the creation of both books. At Wilson’s request, I reviewed portions of his manuscript before publication and provided feedback. I also wrote several of the articles appearing in the JLC book.

A new distributor of building products from Europe has set up shop in Brooklyn, New York. The company, called Four Seven Five, was recently founded by a trio of 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. consultants: Floris Keverling Buisman, Sam McAfee, and Ken Levenson. Four Seven Five plans to import air-sealing products and ventilation fans from Germany, as well as HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. equipment from Denmark.