Building Science.com is an excellent resource for building science. As a firm, Building Science Corporation is a building science consulting and full service architecture firm that specializes in building technology consulting for all types of buildings including commercial, institutional and residential.
Energy Vanguard.com is a great educational site, clearly and succinctly describing the application of building science. And as a firm it provides residential training, consulting, design (HVAC), and HERS provider services.
Green Building Advisor.com is an excellent, pragmatic resource of building science and sustainability. Focusing primarily on residential there are many thoughts, applications and processes that are applicable to commercial and institutional architecture. It is very educational when it comes to application and suitability of enclosure building products.