Occupancy sensors have been installed in 30 buildings on campus. Occupancy sensors can be used in classrooms and offices and are especially effective in areas of short-term and inconsistent use, such as bathrooms, closets, hallways and workrooms.
Buildings are considered on an individual basis to evaluate the potential payback from installing the sensors in appropriate areas. The U.S. EPA estimates that occupancy sensors can save as much as 30 to 50 cents for every square foot.
A common past complaint about sensors was that they turned off when people were still present in the room but not very active. New multi-technology occupancy sensors incorporate both passive infrared and ultrasonic sensors into one unit. This combination of the long-range detection capabilities of passive infrared sensors and the sensitivity to minor movements of ultrasonic sensors allows the units to do a much better job of deciding when to turn the lights on or off.
"Occupancy sensors have been installed in many buildings on campus so that when a room is not being used, the lights turn off. The lights turn on when people enter the room and turn off ten minutes after they leave."—Carl Newton, Energy Reduction Manager (Retired)
Heating, ventilating and air conditioning
Occupancy sensors can be used in tandem with the building automation system to create smart rooms. In this scenario, a room becomes aware that it is occupied and adjusts the interior environment accordingly.
The heating, ventilating and air conditioning systems on campus are another big consumer of energy. There are quite a few items on the list of controlling energy that are being done to reduce energy costs with this equipment. In the past this equipment has been controlled by pneumatic air pressure controls. These are the hissing thermostats that may be heard in some of our buildings. These are inefficient and costly to maintain. Some electric controls are also still in use. The proven technology today is electronic control called direct digital control. These systems are called building automation systems. This technology uses electronic thermostats, sensors, and controllers to operate the heating, ventilating and air conditioning equipment. With these systems controlled through the building automation system, occupancy sensors can be used once a person has entered a room to transition the environment from standby to active. When this happens, the occupied room can be appropriately heated or cooled during off-peak hours during the day. Other green technologies currently in use in on-campus heating, ventilating and air conditioning systems are energy efficient motors and variable frequency drives.