What are the two most effective ways to increase a buildings energy efficiency utilizing the roof? Reflective and vegetative roofing systems! Coated metals, single-plies, shingles & tiles are just a few of the options that can make it a "cool" roof. "Coolness is measured by two properties: solar reflectance and thermal emittance." (source…Mark Robins, Metal Constrcutions News) A cool roof reflects and omits the sun's heat back to the sky. Yes, and this can be done in Michigan!
Vegetative roofs and green roofs are two different systems but have the same purpose. The vegetative roof protects the waterproof membrane from the daily variations of temperatures. The intensive green roofs are thicker and can have a wider variety of plants but require more maintenance. The extensive green roofs use a lighter layer of vegetation and are thinner. There are a lot of variables to look at before deciding if a vegetative roof is the right roof system to use if you live in northern Michigan or not. See the complete article with more detailed information on cool vs.green roofs. http://www.metalconstructionnews.com/articles/magazine-features/cool-vs-green-roofs-how-they-top-out.aspx.