Produced under direction of ComEd by the National Renewable Energy Laboratory (NREL) under Technical Services Agreement TSA-19-01159
The simulation results predict considerable annual energy savings for all the upgrade scenarios. The following energy-saving ranges were observed:
- Annual total building energy savings from 3%–23%
- Annual total building energy savings from 0.1 kWh/ft2–7.6 kWh/ft2
- Annual total building energy savings from 364 kWh/ton–1,146 kWh/ton
- Annual HVAC energy savings ranging from 23%–53%
- Annual supply fan energy savings ranging from 25%–65%
- Annual supply fan energy savings ranging from 954 kWh/BHP–2,842 kWh/BHP
- Peak energy demand savings from 0%–11%
- Peak energy demand savings from 0 W/ft2–1.1 W/ft2
- Peak energy demand savings from 0 W/ton–198 W/ton.
As expected, RTUs with a variable-speed compressor (Case 2 and Case 5) showed superior performance compared to RTUs with single-stage and two-stage compressor. This is a result of enhanced part-load performance due to the improved matching of the compressor capacity with the cooling load.
Similarly, supply fans with SRMs exhibited improved performance compared to the constant- and variable-speed induction motor supply fan cases examined. In all building types, the use of SRMs on the RTU supply fans resulted in 9% extra fan energy savings on average, compared to the supply fan with a variable-speed induction motor.