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Developed in the late 1980s, the transpired air collector is a relatively new solar technology that shows great promise because of its simplicity and low cost. It serves best as a source of preheated air for ventilation, but can also be used as a primary source of space heating. As of 1997, approximately 42 transpired collector systems had been installed. The case studies presented here are two installations that have been monitored extensively.
Case Study: Chemical Storage Facility Achieves 4.7-Year Payback With Transpired Air Collector
NREL Chemical Storage Facility, Golden, Colorado (PDF 594 KB)
The installation at NREL is an ideal application of transpired collector technology. The facility is a 1300-square-foot chemical waste storage building that requires a ventilation rate of 3000 cfm to maintain safe indoor conditions. Also, because of the danger of combustion, open flames are prohibited in the building, so outside air is heated with electricity instead of gas. The 300-square-foot transpired collector saves about 14,310 kWh annually (25.7% of the energy required to heat the facility's ventilation air). With a local electric rate of $0.025/kWh, the annual savings equates to about $360. The installation has a simple payback of 4.7 years.
Case Study: Production Plant Achieves 6-Year Payback On Transpired Air Collector
General Motors Battery Plant, Oshawa, Canada (PDF 594 KB)
The General Motors Battery Plant in Oshawa, Canada, is a 100,000-square-foot facility in which automotive batteries are manufactured. The plant was built in the 1970s and consists of an open shop floor and a 28-foot-high ceiling. The plant's steam heating system was unable to adequately heat the facility. In 1991, the plant installed a transpired air collector, comprising 4520 square feet of absorber sheeting, at a cost of $66,530. The system provides preheated outside air to the plant, operating with a total airflow of 40,000 cfm, of which some may be recirculated air from the plant. The collector has saved the plant 940 million Btu per year, which yields a simple payback of 6 years on the system.
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