SolarVenti by Chesapeake Solar provides controlled ventilation by producing dry, warmed air that can be used for ventilation and supplement space heating/cooling. It keeps the relative humidity of an indoor space between 40 and 60 percent. The self-contained unit continually exchanges the air in the space. The collectors can be mounted on a roof in the same way as hot water or photovoltaic panels. Flexible duct conveys the air into the space.