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It’s no secret that HVAC systems account for a significant percentage of the energy used by a building. But it’s not only the heating and cooling systems that present opportunities for big savings.
Facility executives should also take a close look at the fan systems in a building. In doing so, however, facility executives should understand how the energy consumption of a fan varies with its speed.
The amount of power used by a fan is proportional to the cube of the speed of the fan. That’s counterintuitive. Chillers, for example, use less energy to produce a ton of cooling at full load than at part load. Fans are just the opposite. At full speed, they are at their least efficient. That means even a small reduction in fan speed can produce surprising energy savings.
One option for cutting fan speeds is to install variable frequency drives on fan motors. That way, fans can be slowed down when conditions in the building don’t require them to operate at full speed.