Published in Bolling, A. L., & Mathias, J. A. (2008). Investigation of optimal heating and cooling systems in residential buildings. ASHRAE Transactions, 114(1), 128-139. ©2008 ASHRAE (


This article compares four heating and cooling systems. The systems are: a high efficiency furnace and electric air conditioner; a ground source heat pump; an absorption air conditioner and direct heating; and a thermally driven heat pump; the last two systems use solar thermal energy and backup non-renewable energy. A comprehensive program was developed that predicted the entire life cycle cost, energy usage, exergetic efficiency, and exergy destruction, of all four systems operating in the same home figuratively placed in the cities of Louisville, KY; Houston, TX; Minneapolis, MN; Sacramento, CA; and Phoenix, AZ. The results showed that the vertical ground source heat pump always paid back in the shortest time, between 4-15 years in all five cities compared to the furnace and air conditioner system. The economic pay back period was the shortest between 4- 7 years in the cities of Louisville. Minneapolis, and Phoenix, which have larger heating and/or cooling requirements. The thermally driven heat pump, which largely used renewable energy, had equal or greater exergetic efficiency than the ground source heat pump in each city, while the furnace and air conditioner always had the lowest exergetic efficiency.