Published: March 3, 2016
Exhaust hood airflow is a major contributor to energy use in commercial kitchens. Typically an exhaust hood is turned on at the beginning of the workday and runs at full speed until it is turned off at the end of the day. A make-up air unit linked to the exhaust hood will also run at full speed during these hours of operation in order to resupply semi-conditioned outdoor air to replace the air being exhausted. Running both fans continuously at full speed wastes substantial energy as the need for exhaust air is variable, fluctuating up and down based on cooking load.
A solution to this problem is exhaust hood control. Exhaust hood control varies the exhaust fan airflow based on cooking load, using variable frequency drives to modulate fan speed. The exhaust hood controls can similarly regulate the speed of the make-up air unit fan supplying outdoor air to the kitchen hood. Controlling fan speed results in fan energy savings, and heating and cooling savings if the make-up air unit is also controlled. The figure below shows the savings possible from controlling kitchen exhaust hoods.
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BUILDING DESIGN / ENVELOPE
HEATING / COOLING