A side-by-side field test of a commercially available variable-speed, variable-capacity (VSVC) air conditioner (AC) and a conventional, constant- speed (CS) air conditioner was undertaken. The test took place in two adjacent classrooms at a university in Melbourne, Florida, from June to November 1988. The VSVC AC unit was found to use 40% less total energy (kWh) during occupied periods and 59% less kWh during unoccupied periods. During the occupied period, the average measured EER for the VSVC AC unit was also 17% higher than for the CS AC unit. These results are in line with the differences expected from the SEER rating. The comfort conditions of the space (humidity) were not maintained by the VSVC AC unit. It is unclear whether poor humidity control was inherent to the unit or due to the highly variable nature of the load.

KEYWORDS: constant volume air conditioning, USA, comparing, testing, site testing, variable speed motors, comfort, air conditioning, variable volume air conditioning, energy consumption.