Recently, Dillards in Naples, FL needed to replace their aging rooftops with new equipment. With energy savings in mind they decided to use AAON Single Zone VAV rooftop equipment. Single Zone VAV operation controls to a constant discharge air temperature (typically 55F) and modulates the supply fan based off of space temperature between 30-100%. For DX equipment to do this requires a variable capacity compressor to maintain a constant discharge air temperature and a variable frequency drive on the supply fan to vary the speed of the fan.
Design:
For their 180,000 sqft facility Dillards choose to use 10 AAON RN 40 Ton rooftops to condition their sales floor and 1 AAON RN 15 ton rooftop for their office space, all units came equipped from the factory with digital scroll compressors and direct drive backward inclined fans with variable frequency drives.
Results:
5 months after the initial install, with the peak cooling behind Dillard’s recorded energy savings of 23% in their overall electrical use, 20% reduction in kWh/sqft and a 22% reduction in their peak demand.