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General Limit States Design, Hygrothermal AnalysisAt a basic level a wall is an environmental separator.  It keeps the outside out and the inside in.  Easy to say, not always easy to do.To function… Read More

“gas separation processes and open cell low density spray foam”1Lots of attics insulated with open cell low density spray foam (Photograph 1, Photograph 2 and Photograph 3) are having problems – in… Read More

There.  I said it.  It just does not work.  OK, it works sometimes1.  But it does not work in tight building enclosures and certainly not in new houses, apartments, townhouses and row houses. … Read More

Water causes enough trouble by itself, but when we add salt we go to a whole different level, especially where porous materials are concerned. What is the deal with porous materials? Simple, porous… Read More

* Credit to architect Edward Mazria: I think he said this first, if he didn't say it first he sure says it well.Many “green” buildings don’t save energy (see “MIS-LEED-ING” sidebar). Why? They have… Read More

For a bunch of supposedly clever folks we sure do dumb things. One of the big ideas of the past couple of decades or so is to keep the heat out during cooling and keep the heat in during heating. The… Read More

The perfect wall is an environmental separator—it has to keep the outside out and the inside in.  In order to do this the wall assembly has to control rain, air, vapor and heat. In the old days we… Read More

The energy used in institutional, commercial, and industrial buildings in cold climates (zone 4 and above) is substantial. Most of this energy is used after construction is complete; hence, reducing… Read More

Putting metrics on building energy performance is a required step to make any progress on low-energy use and/or “green” buildings. However, there are many confusing and contradictory metrics… Read More

The difference between site and source energy is a vital concept to understand when looking at the energy performance of buildings—failing to account for the difference will result in an apples-to-… Read More