Saving Energy Using Electronically Commutated Motors to Run Indoor and Outdoor HVAC Blower Fans
Electric motors account for almost one third of commercial electrical energy consumption. HVAC and refrigeration equipment are the largest users of motor-driven energy consumption in the commercial sector.
The ASHRAE 90.1 2013 standard requires that fan motors greater than 1/12 horsepower and less than 1 horsepower be electronically commutated motors (ECMs) or have a minimum efficiency of 70% with a means to vary speed. Newly installed HVAC systems will possess variable speed capabilities, but the majority of existing systems continue to operate with older fixed speed fan motors resulting in excessive energy consumption.
Commercial unitary air conditioners and heat pumps (CUAC) contain three motor-driven components: the compressor, indoor blower, and outdoor blower. The outdoor blower may have multiple fans and motors depending on the capacity of the unit. Permanent Split Capacitor (PSC) motors are typically used for the outdoor fans and range from 0.25 to 1 horsepower, while the indoor blowers are typically driven by three-phase AC induction motors ranging from 1.5 – 7.5 horsepower. Because the CUAC fan motors are low horsepower, it is recommended to use ECM technology for indoor and outdoor blower fans. Average energy savings per horsepower can exceed 3,500 kWhs per year. As the capacity of the CUAC fan increases, the energy savings increases. In fact, the payback period of upgrading 1 horsepower blowers to ECMs can be less than one year.
Do you have a project that can benefit from this technology? Contact the Air Northwest team or your utility and we will help you figure out if there are any incentives available for the project.
Source: DOE Energy Efficiency & Renewable Energy Building Technologies Office, Energy Savings Potential and Opportunities for High-Efficiency Electric Motors in Residential and Commercial Equipment, December 2013