Climate Appropriate HVAC

Residential and commercial heating, ventilation and air conditioning (HVAC) units account for a significant load in Southern California Edison’s (SCEs) service territory. The energy usage of these Heating, Ventilating, and Air Conditioning (HVAC) units coincides with higher temperatures (in cooling mode) or lower temperatures (in heating mode). The SCEs grid system identifies these high/low temperatures as “peaks in demand”. Efficiency improvements in HVAC technologies reduce these peak demand issues and reduce the overall energy consumption on a yearly basis. A typical residential air conditioning unit absorbs heat from the residence and rejects it to the ambient in cooling mode. The higher the ambient temperature, the more effort it takes the unit to reject the heat to the ambient in cooling mode. Hot Dry Air Conditioners (HDAC) claim increased energy efficiency and reduced demand at higher ambient temperatures by using evaporative cooling. Evaporative cooling of a condenser can locally reduce the ambient temperature, reducing the energy input required for conditioning a given space. The evaporative cooling effect is caused by evaporating water on the condenser coils, thus reducing the temperature seen by the condenser closer to the wet bulb temperature of the ambient air. Water is also used to purge the internal reservoir for this type of condensing unit. Field installation of HDAC units answer key questions related to this technology, specifically, the comparative performance of baseline air-cooled units and the water consumption due to evaporation and purging. The goal of this project is to determine the viability and capability of the HVAC industry infrastructure to install, operate, and maintain equipment designed and engineered for hot and dry climates. This project monitors the feasibility of an evaporatively cooled condensing unit in a real world application found in Southern California Edison’s service territory. The project focused on climate zone 14, representing medium to high deserts. This climate zone is characterized by wide swings in temperature, with hot summer days followed by cooler nights. Another objective of this project is to develop additional data points from field installations in order to validate the savings reported in an earlier PIER study and help develop the necessary support documentation and building simulations required to facilitate the development of an energy efficiency program. A corollary of this project is to correlate and validate the field monitoring results with laboratory results conducted under a complementary project at SCE's Refrigeration and Thermal Test Center.