generally described as complete removal of the existing air handling unit (AH-1) and return air fan
(F-9) and replacement with new similar units.
The unit was equipped with both a supply and a return air fan
, at fixed speeds, which combined could deliver 3817 cfm (1,801 l/s) at 2" (50 mm) wc external static pressure--this arrangement was changed part way through the monitoring period to reduce total airflow and overall electrical energy consumption.
rf, N] = Electric power of supply and return air fan at Nth cooling stage, kW
The breakpoint is determined by comparing the total electric power without mechanical cooling to that with the first stage of cooling, where the supply and return air fans power using high supply air temperature exceeds the total electric power of the refrigeration system, the supply and return air fans using low supply air temperature.
The RTU was equipped with both supply and return air fans
and configured as a VAV system with 100% economizer capability.
The difference in total brake-horsepower (BHP) between system comparisons must consider supply and return air fans
and heating hot water and chilled water pumps.
The conventional method of reducing energy consumption is to install variable frequency drives (VFDs) on the supply and return air fans
and convert the terminal box.