Photograph by Kristina DeMichele/ Harvard Magazine. Located at 60 Stearns Street, the building is expected to achieve both LEED Platinum and Passive House certification. The LEED (Leadership in Energy and Environmental Design) program promotes environmentally and socially responsible building and community living through a rating system based on the number of green-building strategies utilized. Ratings range from Certified to Silver, Gold, and Platinum; of the 110,000 LEED-rated buildings in the United States, only 6 percent have earned the Platinum designation. Air compressors outside the home Photograph by Kristina DeMichele/ Harvard Magazine. To obtain Passive House certification from PHIUS, additional stringent metrics must be met. Continuous filtered ventilation to every room ensures significantly better indoor air quality than that found in typical construction, while the exacting air-tightness requirements necessary to meet the standard demand a combination of air-sealing and moisture-wicking materials. The house has nine cooling and heating zones, with fresh air circulating constantly. An ERV (energy recovery ventilator) extracts heat from air leaving the house and transfers that heat to the incoming air. The ventilator operates continuously but uses minimal energy.