Notes that a heating penalty is expected when economisers are applied to dual-duct air handling systems. States the heating penalty can be even higher than the cooling savings when the hot air flow is higher than the cold airflow. Describes advanced economisers to avoid the excessive heating penalty. Describes an application of the economiser which has resulted in savings of $7,000/yr in one 95,000 ft² (8,800 m²) school building since 1993. Also discusses the impacts of the cold and hot deck settings on energy consumption.

Units: Dual

KEYWORDS: year 1997, Economisers, heat exchangers, air handling units, dual duct air conditioning, energy consumption, energy conservation, schools, USA