“Build tight, ventilate right” is an often-repeated motto of those who consider energy efficiency and comfort as critical to the success of any building project. “Build tight” refers to building a well-insulated, and airtight, envelope (walls, roof, floor, etc.) to separate uncomfortable outdoor weather from comfortable interior air. “Ventilate right” recognizes that human occupants need clean fresh air to breathe but refers to intentional controlled ventilation rather than relying on leaky construction and wind.