It also can be an extremely efficient method. We love this prototype designed by students from Appalachian State University in Boone, North Carolina, and their peers from the Université d’Angers in France for the 2014 iteration of the Solar Decathlon Europe in Versailles, France. The super green design consists of three layers: an energy-efficient, insulating structural envelope, an integrated building systems core with the mechanical, electrical, and plumbing systems, and an exterior shell equipped with solar systems and the ability to shade and collect rainwater.  Photo 4 of 6 in 5 Things You Should Know About Modern Prefab Construction