Musings of an Energy Nerd

My grandfather, William L. Holladay, was a refrigeration and cooling engineer. Decades ago, he wrote a pioneering, speculative article on ground-source heat pumps, “The Heat Pump: What it does, and what it may do someday.” The article appeared in the October 1948 issue of Engineering and Science Monthly. (For a basic explanation of how a heat pump works, and the difference between an air-source heat pumpHeat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps. and a ground-source heat pump, see Heat Pumps.)

Stuffy homes are unhealthy homes, while homes with plenty of fresh air are healthy. That’s been a commonly held belief for at least 200 years. In the mid-19th century, the connection between ventilation and human health was championed by sanitarians, a group of health experts who blamed the spread of bubonic plague and cholera on “miasma.”

There are lots of reasons to attend conferences. At a good conference, we get a chance to network with colleagues, to learn about recent research, to see new products, and to talk with manufacturers' reps. I've had the good fortune, over the last six weeks, to attend three conferences focusing on green building and residential energy:

UPDATED June 17, 2013 with new product information

Twenty years ago, very few residential builders knew what a rainscreenConstruction detail appropriate for all but the driest climates to prevent moisture entry and to extend the life of siding and sheathing materials; most commonly produced by installing thin strapping to hold the siding away from the sheathing by a quarter-inch to three-quarters of an inch. was. These days, however, it’s no longer unusual to see siding being installed on vertical furring strips or a plastic drainage mat. As rainscreens become more common, mainstream builders are beginning to ask, “What’s a rainscreen? How do I know if I need one?”

This article will pull together information to answer the most common questions about rainscreen gaps between siding and 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. .

I first heard about the problem of smelly fiberglass batts from Michael Maines, a builder and GBAGreenBuildingAdvisor.com blogger who lives in Portland, Maine. Maines sent me an e-mail saying, “The latest problem with fiberglass insulation is that it smells like burnt brownies!”

I’ve collected a half dozen reports of this problem, all centering on EcoTouch brand fiberglass batts manufactured by Owens Corning. Two years ago, the company switched from a formaldehydeChemical found in many building products; most binders used for manufactured wood products are formaldehyde compounds. Reclassified by the United Nations International Agency for Research on Cancer (IARC) in 2004 as a “known human carcinogen."-based glue (or binderGlue used in manufactured wood products, such as medium-density fiberboard (MDF), particleboard, and engineered lumber. Some binders are made with formaldehyde. See urea-formaldehyde binder and methyl diisocyanate (MDI) binder. ) to a new glue described as a “bio-based” binder.

Most builders and designers involved with green building have heard of Henry Gifford. Energy efficiency experts admire his deep knowledge of heating systems and his straight talk about the unacceptably high number of HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. problems in run-of-the-mill new buildings in the U.S. At the headquarters of the United States Green Building Council (USGBCUnited States Green Building Council (USGBC). Organization devoted to promoting and certifying green buildings. USGBC created the LEED rating systems.), on the other hand, he is something of a pariah — due in part to his 2010 lawsuit that accused the USGBC of making “deceptive marketing claims.”

Every couple of weeks, someone sends me an e-mail with a description of a proposed wall assembly and an urgent question: “Do I need a vapor retarder?” Energy experts have been answering the same question, repeatedly, for at least thirty years. Of course, even though I sometimes sigh when I read this recurring question, it’s still a perfectly good question.

A discredited theory of embryonic development held that “ontogeny recapitulates phylogeny” — in other words, that the the developmental stages of an embryo (its ontogeny) mimic the stages of evolutionary development experienced by the species (its phylogeny). One piece of evidence supporting the theory: in early stages of development, a human embryo has a tail.

With apologies to Dr. Seuss

From 1977 (when the Saskatchewan Conservation house was built) until 2004 (when the first U.S. Passivhaus was built), North American builders completed hundreds of superinsulated homes. In those days, anyone interested in rating the performance of these homes was probably interested in just one metric: annual energy use.