Scheduling exhaust fans – an easy way to save money

Have you ever taken a walk on the rooftop of your hospital or clinic to see what is up there? You might be amazed at the amount of heating, ventilation, and air conditioning equipment that is placed on rooftops. This is often a good place to install mechanical systems since rooftop space is not in high demand. Exhaust fans can range in size and shapes from a very small unit such as those you might find in your home to fans the size of the one in the photo above. Sometimes you may find small exhaust fans mounted to ductwork through exterior walls of buildings. Their functional purpose is to exhaust air from inside the building. They are frequently used remove fumes, odors, particles, etc. from inside the building and thus improve the indoor air quality for occupants. In certain applications, such as pharmacies that mix chemotherapy drugs, isolation rooms, labs, etc. exhaust fans may serve an important safety or infection control function. There are many fans that serve restrooms and cafeteria cooking areas.

Exhaust Fan

However, “out of sight” typically means “out of mind” and when energy use is invisible to us we usually don’t manage it very well. When Gundersen Health System began its Envision® program in 2008 we started with an intense energy efficiency effort. One of the steps we took was to inventory our exhaust fans. We found that we had over 300 exhaust fans serving our six largest facilities…approximately 1,500,000 square feet of mixed-use inpatient, outpatient, and medical office buildings. That was a surprising number of fans, but what was even more surprising was that most of these exhaust fans were operating 24 hours per day, 7 days per week even though most were serving areas that were unoccupied for at least 10 or 12 hours each day. If you think about it, nobody leaves their bathroom exhaust fan running when they leave their home for the day. Why should we have these exhaust fans using energy when it isn’t needed? Energy waste costs money which is passed along to patients, contributes to disease, and harms the environment.

Electronic controls can make automatic scheduling of fans easy so they can be turned off when they aren’t needed–although they are frequently installed without electronic controls. However, some fans may have electronic controls and others may make sense to retrofit with new controls so they can be scheduled. On one of our buildings, our fan inventory revealed eight fans similar to the one in the photo that could be automatically scheduled and instantly provided an annual energy savings of more than $5,000. This is an easy way to improve health, save money for patients, and improve the environment.


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