Solar-Powered Environmental Control Unit for Commercial Buildings

ABSTRACT: Using solar energy to drive air conditioning systems is logical since the sun is present when air conditioning is needed the most. Unfortunately, the payback period for installing photovoltaic solar cell arrays to electrically drive the air conditioning system is unacceptably long, at least two decades. However, solar collector (fluid heating) and absorption air conditioning cycle efficiency, cost, and reliability have improved sufficiently over the past decade to allow direct replacement of electric-powered vapor-compression cycles with solar heat-driven absorption cycles. Mainstream"s proposed Solar Environmental Control Unit (SECU) uses solar energy to power an absorption air conditioning system when cooling is required, or circulates the hot, solar-heated fluid to heat the indoor air directly at moderately cool outdoor air temperatures. When the heat input by solar irradiation is insufficient for either cooling or heating the building, supplemental heat is supplied by efficient, clean-burning natural gas. Applying the assumptions detailed in this proposal, Mainstream"s SECU has a payback period of about 10 years when compared to a 13 SEER vapor-compression cycle in Warner Robins, GA. Renewable energy rebates/credits or waste-heat utilization could also reduce the payback period substantially BENEFIT: Mainstream"s SECU system will substantially reduce electricity costs for building heating and cooling. The total life cycle cost (installed + operating costs) for heating and cooling is also reduced. Additionally, reducing energy consumption for environmental control during the peak hours will minimize peak power grid burden. Greenhouse gas emissions from consumption of non-renewable electrical power for heating/cooling are also minimized.