Why can a modulating air-conditioning compressor reduce energy use at partial cooling loads compared with a single-speed compressor?
- AIt always operates at maximum output
- It adjusts its output to better match the cooling demand
- CIt eliminates the need to select an appropriate system size
- DIt guarantees the highest efficiency regardless of installation
Where to look it up
https://www.energy.gov/cmei/femp/purchasing-energy-efficient-light-commercial-heating-and-cooling-equipment
Why B is correct
DOE identifies compressor modulation as a way to reduce energy use at partial loads. It does not establish that every variable-speed model outperforms every other unit: climate, sizing, controls and installation still matter. Source: https://www.energy.gov/cmei/femp/purchasing-energy-efficient-light-commercial-heating-and-cooling-equipment