On the roof at the project house in Weston, plumbing and heating expert Richard Trethewey shows host Kevin O'Connor the new solar hot water system that makes use of evacuated tube technology—the perfect solution for a cold climate. General contractor Tom Silva gives homeowner Amy Favat a progress tour of the house. The rough plumbing and electrical are nearly complete, the cabinets are in, and the concrete countertop fabricators are on site to template for the tops, which will take four to six weeks to make and to cure. At the Bensonwood shop in New Hampshire, Tom lends a hand to finish carpenter Dennis Wright as he installs "home slicker" and pre-stained white cedar shingles to the exterior wall panels. Back in Weston, plumbing contractor Lynne Keating shows Richard how the plumbing connections are made on the prefab floor panels.