Musings of an Energy Nerd

Martin’s Ten Rules of Roof Design

Posted on December 9, 2011 by Martin Holladay, GBA Advisor

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.

Books on Insulation and Energy-Efficient Building

Posted on December 2, 2011 by Martin Holladay, GBA Advisor

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.

European Products for Building Tight Homes

Posted on November 25, 2011 by Martin Holladay, GBA Advisor

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.

How to Build an Insulated Cathedral Ceiling

Posted on November 18, 2011 by Martin Holladay, GBA Advisor

UPDATED on September 12, 2014

Although the website already contains many articles on the topic, we continue to receive frequent questions about the best way to insulate a cathedral ceiling. It’s therefore time to pull together as much information on the topic as possible and publish it in one place, to clarify the building science issues and code requirements governing insulated sloped roofs.

More Energy Myths

Posted on November 11, 2011 by Martin Holladay, GBA Advisor

Energy myths are persistent, in spite of the fact that energy experts spend a good deal of time performing debunking duty. Many energy experts collect misguided energy-saving tips as a hobby, and pick the myths apart with the dedication of an 18th-century amateur scientist.

In a previous blog, I presented my own list of ten energy myths.

Guardian Fiberglass Threatens Blogger With Legal Action

Posted on November 4, 2011 by Martin Holladay, GBA Advisor

UPDATED 11/8/2011: Guardian Building Products has apologized to Allison Bailes. See full information at the end of the article.

On October 19, 2011, blogger Allison Bailes, a frequent contributor to, posted a blog on his Energy Vanguard website about the difficulty of installing fiberglass batts well. You can read his excellent blog here: A Visual Guide to Why Fiberglass Batt Insulation Underperforms.

BEopt Software Has Been Released to the Public

Posted on November 4, 2011 by Martin Holladay, GBA Advisor

UPDATED February 1, 2012

In 2004, researchers at the National Renewable Energy Laboratory (NREL) developed BEopt, a software program that finds the least-cost solution to designing a zero-energy house. Now that the software developers — a team that includes Craig Christensen and Scott Horowitz — have spent seven years improving the program, it has finally been released to the public. The development of BEopt was funded by the U.S. Department of Energy.

Scary Stories for Halloween

Posted on October 28, 2011 by Martin Holladay, GBA Advisor

What’s scary for a green builder? Mold in the crawl space?

Naw — mold is a routine problem. What’s really scary is the end of the world as we know it.

A decade or two ago, the end of the world as we know it was a matter of concern for a few nutty survivalists in Idaho. Now it is a matter of discussion at academic conferences.

Several mechanisms have been proposed for the coming economic collapse. Some are based on New Age nonsense, while others are based on hard science.

Martin’s 10 Rules of Lighting

Posted on October 21, 2011 by Martin Holladay, GBA Advisor

Most homes use too much energy for lighting. According to the U.S. Energy Information Administration, the average American household uses 1,667 kWh per year for lighting, which amounts to 15.3% of residential electricity use. Ironically, this energy devoted to lighting is used inefficiently, so the usual result is a dim house with dark, depressing corners.

Membranes réfléchissantes: une solution en quête d'un problème

Posted on October 20, 2011 by Martin Holladay, GBA Advisor

Une membrane réfléchissante est un panneau brillant ou une membrane souple qui est utilisé dans la construction. Bien que la résistance thermique (valeur R) de ces membranes est à peu près de zéro, elles peuvent être utilisées comme partie d'un assemblage en construction — par exemple, un ensemble constitué d'une pellicule radiante et d’un espace d'air — pour ralentir le flux de chaleur.

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