THE PRODUCT:
Water-cooled and evaporatively-cooled commercial unitary air conditioners (WCUACs and ECUACs) and heat pumps (HPs) are very similar to air-cooled rooftop units (RTUs). However, water-cooled units reject heat to water (rather than to air), and evaporatively-cooled units spray water on the condenser coil to help remove heat using the latent heat of evaporation. These products are typically used to cool small- to mid-sized commercial buildings such as schools, restaurants, big-box stores, and small office buildings. WCUACs and ECUACs and HPs are far less common than air-cooled units.
WCUACs and ECUACs and HPs are a category of ASHRAE equipment.
THE STANDARD:
The current standards for WCUACs and ECUACs took effect in 2013 for certain equipment categories and in 2014 for others. The EER standards are identical to the levels in the 2010 version of ASHRAE 90.1. There is no standard for heating performance for heat pumps.
In 2021, DOE issued a final determination not to amend the standards for WCUACs and ECUACs.
*The cooling energy efficiency metric, energy efficiency ratio (EER), is expressed as the cooling capacity (Btu/hr) divided by the power input (watts).
KEY FACTS:
Water- and evaporatively-cooled CUACs and HPs are generally more efficient than air-cooled equipment. Water-cooled air conditioners can be used effectively in any type of environment, while evaporatively-cooled air conditioners are most effective in hot-dry climate regions.