> So far, it has been defined by the German standard that limits the heating and cooling load to 4,755 British thermal units per square foot (or 15 kilowatt hours per square meter)—about one-tenth that of homes built to current U.S. codes.

In the comments section, there's a clarification that this is per year. (Kind of a shame to see "unit fail" in a publication that should know better.)

I'm kind of curious to know what sort of new technology (if any) makes high-efficiency targets easier to meet these days. The article talks about triple pane windows and thick walls. Are these stick-frame houses with fiberglass and offset 2x6s in the walls or something like that, or are there new materials? I recently read that aerogel has been coming down in cost to the point where it's plausible that someone with deep pockets might insulate their house with it if they didn't want super thick walls. Insulated concrete forms and autoclaved aerated concrete are also something that some builders use. What else is new?