8 Passivhaus Cold Climate Building Envelopes Compared & Contrasted
Originally published by: Journal of Light Construction — December 4, 2014
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In the Nov/Dec issue of Home Energy, Rolf Jacobson of the Center for Sustainable Building Research (CSBR) at the University of Minnesota, outlines his research examining the performance of eight different Passive House Walls systems, each with an R-value of about 60.
These included five built in the U.S.:
- a TJI frame with blown-in fiberglass insulation, built in Urbana, Illinois;
- an insulating concrete form (ICF) with exterior expanded polystyrene (EPS), built in southern Wisconsin;
- a structural insulated panel (SIP) filled with urethane foam with an interior 2 x 4 wall filled with blown-in cellulose, built in Belfast, Maine;
- an advanced 2 x 12 stud framing filled with open-cell spray foam and insulated on the exterior with either EPS or vacuum insulated panels (VIPs) built in Bemidji, Minnesota;
- and a double 2 x 4 stud wall insulated with blown-in cellulose, built in Duluth, Minnesota.
And three built in Scandanavia (in climates not unlike Minnesota's):
- an advanced frame with cross-strapping and mineral wool insulation;
- a mass wall that includes 6 inches of concrete and mineral wool insulation;
- and a structural panel, known as Massivtre, that is 4 inches thick with a core made from low-grade wood and an interior surface made from higher-grade wood that provides a nice wood wall finish. The Massivtre wall is insulated with exterior mineral wool.
In the end, each envelope has its own strengths and weaknesses, says Jacobson, and you have to match those to your project, your budget, and the experience of your contractor. For builders who want to achieve really good performance but aren’t comfortable experimenting with too new an approach, the Scandinavian stud wall with the interior cross-strapping is a good option. It’s easy, and the cross-strapping can protect the air barrier and vapor retarder membrane from puncture. Read more to see illustrations of each home.
Jacobson's thesis, "Performance of 8 Cold-Climate Envelopes for Passive Houses," has been published in English by GRIN Publishing of Munich, Germany, where it is available as an e-book.