Partner: National Renewable Energy Laboratory
ComEd's research partnership with NREL examined the energy and peak demand savings potential of new rooftop unit (RTU) technologies.
This project was part of a four-stage effort by ComEd to evaluate the energy-savings potential of emerging technologies in the Chicago area. The first stage evaluated the potential for energy and peak demand savings of RTUs, including:
- Two-stage RTUs
- Variable-speed compressor RTUs
- Switched reluctance motor (SRM) RTU supply fans
Simulation results revealed that upgrading an RTU with a variable-speed compressor and SRM supply fan can result in annual HVAC energy savings of 23–53%, depending on the application. Among building types, standalone retail buildings had the highest total energy savings (53%) while warehouses had the least (23%).
Compared to RTUs with two-stage compressors, variable-speed compressor RTUs delivered an average of 3.2% greater annual HVAC savings per building. Using SRMs boosted savings even higher, with an average of 7.7% compared to variable-speed units.