Blu Homes in Waltham, Mass., features four green prefab models, ranging from the low-cost Origin (pictured), starting at $109,000 for a completed home, to the single-story Element, which starts at $125,000, to the Balance, starting at $270,000. All are LEED certifiable, depending on the finishes, building systems and site design the buyer chooses. The Origin comes in three compact sizes and multiple floor plans that can include one or two bedrooms. It can even be combined with other Blu Homes models for some custom versatility. Eco-features in all models include bamboo floors, stainless steel EnergyStar appliances, metal roof with 50-year life span equipped for solar hot water and photovoltaic energy generation, low- or no-VOC interior primers and paints, and low-flow water fixtures. They also are designed to take advantage of natural light for passive cooling and heating. Homes are available anywhere in the continental United States.