Field Evaluation of a Near Zero Energy Home in Oklahoma

The authors evaluated a Zero Energy Home (ZEH) built by Ideal Homes in Edmond, Oklahoma, that included an extensive package of energy-efficient technologies and a photovoltaic (PV) array for site electricity generation. The ZEH was part of a Building America (BA) research project in partnership with the Building Science Consortium to exhibit high efficiency technologies while keeping costs within the reach of average home buyers, and was a modified version of a production 1584-ft², three-bedroom, single-story, slab-on-grade design with attached garage. The home included a tight, well-insulated envelope, an energy recovery ventilator, high-performance windows, tankless gas water heater, efficient lights and appliances, and a ground source heat pump (GSHP). We conducted a series of short-term tests beginning in August 2005, and have collected long-term data under occupied conditions since February 2006. The GSHP performance was disappointing until the outdoor unit was replaced, after which time the efficiency began to meet expectations. However, the electricity use of the replacement unit was higher than expected because of an unusually low cooling setpoint. Based on the measured test results, the predicted whole-house energy savings compared to the BA Benchmark was 96%, with savings of 55% for efficiency measures alone.