A premium-efficiency fan motor can cost about 25% more than a conventional motor, but can save you a lot of money in annual operating costs. The annual cost of the energy it takes to run an electric motor continuously can be about 6 to 8 times the purchase cost of the motor. Replacing a working motor (unscheduled replacement) with an energy-efficient motor can also have an attractive payback when the motor is used more than 4,000 hours per year. With this in mind, you will probably find that it makes sense to purchase an energy-efficient motor, rather than rewind a conventional one.

Variable Air Volume System
The air supplied by building fans is sized to provide cooling on the hottest days. However, on mild days, the volume of air required is considerably less. If your building is equipped with a constant air volume (CAV) system, in which the fans run at a constant speed, the system is supplying more air than is necessary most of the time. The conversion of the older constant volume system to a modern, energy-efficient variable air volume (VAV) system is a task to be taken with serious consideration and expert analysis. This would normally require the services of an engineering firm.

Variable Speed Drives
Inlet guide vanes on variable air volume (VAV) air handlers do a good job of reducing airflow. A variable speed drive (VSD), however, saves much more energy while controlling the airflow. The VSD controls air flow by adjusting the fan speed electronically. The ENERGY STAR® Business Program offers QuikFan, a free software tool allowing you to analyze the cost-effectiveness of upgrading variable air volume (VAV) water flow systems. The primary focus of QuikFan is the application of variable speed drives (VSD) to fan and pump motors. QuikFan is available from the ENERGY STAR® Buildings Program on-line.