Hybrid Heat Pump and Indirect Evaporative Cooling Packaged Unit (Hybrid RTU)

Rooftop packaged units (RTUs) provide heating, ventilation, and air conditioning for approximately 75 percent of commercial building floor area in California. This project laboratory tested a commercially available Hybrid RTU that includes a heat pump and Indirect-Direct Evaporative Cooling across a range of outdoor conditions that match California climate zones. This Hybrid RTU can replace conventional RTUs on commercial buildings.  For common California outdoor conditions of 95°F dry bulb, 50°F dew point humidity, the Hybrid RTU has a room (system) cooling capacity of 4.60 (4.85) tons and coefficient of performance (COP) 4.19 (4.42) with 56% outdoor air ventilation fraction.  The measured results were used to develop performance curves and lookup tables that will be used by future projects to estimate energy savings using Energy-Plus and CBECC-Com.