Harold Turner’s home near Concord, New Hampshire measures 3,370 square feet and was built using the ROSE construction method, which was created to build affordable net zero energy and cost effective homes in a wide variety of geographical locations and environments. R stands for “Renewable energy production,” O and S stand for “Owner driven spatial design,” and E is for “Energy efficient construction,” while the entire house is known as ROSE cottage and serves as a prototype and test bed for future homes to be built using this method. The entire home was built for $175 per square foot.
The shell of ROSE cottage is airtight, which was achieved through the use of cellulose fibers, expanding polystyrene and mineral wool to insulate the walls, floors and roof. The home was also fitted with double and triple glazed windows. The home is not quite a Passive House, but it does have walls with insulation values of R-40, while the roof is R-60 and there is R-22 under the slab. In addition, the windows and doors were placed with careful consideration for maximizing natural daylighting in the cottage.
ROSE Cottage is powered by a 13.8 kW photovoltaic array mounted on the garage. There are also Solectria inverters connected to the PV array and then via aby-directional smart meter (to the utility grid. For emergency situations, the house also has a bank of 16 DC, 60 amp-hour batteries connected to the PV system through two 3,600W DC Outback inverters, which can supply up to 7,200W of back-up emergency power.
The house is heated by two Bosch ground source heat pumps. One of these supplies the hot water for the radiant floor heating system, while the other heats the air. The heat pumps don’t use wells, as conventional ground source heat pumps do, but instead has horizontal pipes, which are laid in a sand bed under the slab. The house also features a Bosch Buderis solar thermal system, which is tied into the heat pump system. Excess heat produced by the hot water system is pumped into the ground bed, where it is stored to minimize wastage.
The cottage is ventilated by the use of a Fantech SHR3005R dedicated air-to-air (92% efficient) heat recovery exchanger and a Fantech HEPA filter air supply system. Also, only zero VOC Glidden Professional paints and Executive Cabinetry cabinets were used throughout the cottage to minimize or eliminate toxic air pollutants.