What is it?
Advanced modulating air conditioning compressors allow air conditioners, both residential and commercial, to respond more efficiently to changes in cooling loads. These compressors can change their speed or capacity by using mechanical unloading or variable speed drives. As cooling loads vary, the compressor power and output also vary. This technology allows for seasonal energy efficiency ratio (SEER) ratings much higher (18-20+) than previous technology allowed (SEER of 13-15).
How does it work?
Compressors are the “engine” of all cooling systems, moving refrigerant through the system. Most compressors run at one speed (RPM) and cycle on and off as needed. Think of modulation as either a transmission (unloading) or throttle (variable speed). Unloading will still have a constant motor speed (RPM), but different “gears”, or unloading steps, allow the compressor capacity to change based on load. Variable speed control is like using the gas pedal, where the speed (RPM) changes up or down continuously as needed while in the same “gear”.
What are the most appropriate applications?
Residential and small commercial facilities are the most applicable for this technology, but all facilities with small, packaged cooling systems can benefit.
What are the savings?
Energy savings for this technology occur whenever cooling loads are lower than design capacity, which is the majority of the cooling season. Air conditioning equipment with modulating compressors will have higher SEER values. A typical three-ton residential air conditioning unit will save about 1,100 kWh per year (~$120) if it is a 19 SEER modulating unit instead of a standard 13 SEER unit.
What are the non-energy benefits?
Modulating units allow for tighter control of space temperatures and humidity by running for longer periods of time and adjusting output based on loading. This improves comfort levels and contributes to longer compressor life due to fewer on/off cycles.
What is the cost?
The incremental cost of modulating air conditioning units over baseline units ranges from $200 to $500 per ton, with the incremental cost increasing with SEER.
What is the status/availability of the technology?
This technology is readily available through multiple vendors.
What kinds of incentives/programs are available?
This technology is rebated through the Standard Rebate program for air conditioners from 14.5 to 18 SEER. Units 19 SEER and higher are currently incentivized through the Custom Rebate program.