Heating is provided by a high-performance air source heat pump and will supply hot water to radiant tubing throughout the house – radiant concrete slab at the first floor, radiant ceilings at the second floor. Yes, this house is heated by electricity! Electric space heating works for this project due to extremely low heat-loss provided by the very-tight, well-insulated building envelope coupled with a 7.2 kilowatt, grid-tied solar PV system. The building envelope walls are super-insulated with 12” SIPs (Structural Insulated Panels – 11.25” rigid foam faced with 1/2” OSB sheathing) for a total wall R-value of 49. Roof insulation is a hybrid system of 12” SIPs and cellulose for a total R-value of 98. Subslab and slab perimeter insulation is R30.
About 70% of the electric power consumed in the house, which will be equipped with fluorescent and LED fixtures throughout, will be generated by a 7.2 kW photovoltaic system. Excess power from the PV system is purchased by the utility company and fed back into the grid. This system will generate roughly 8,830 kilowatt hours of clean electricity annually and offset roughly 11,479 lbs. of CO2 emissions annually.
Domestic hot water will be generated by flat plate solar thermal panels (2) that preheat the water, backed up, as necessary, by a 119 gallon solar storage tank with integral electric element. Insulated pipes and an on-demand pump efficiently distribute the hot water. This system will produce roughly 11,592,000 Btu’s of clean, renewable energy annually and offset 4,906 lbs. of CO2 emissions annually.
Total annual energy costs for this house are estimated to be less than $1,000.
Future posts will include detailed presentations of each system.