Almost all buildings, in particular hospitals, have a Building Automation System (BAS). It’s is like the brain of a building. BAS controls most HVAC devices, such as pumps, fans, boilers and chillers. It is an interconnected, centralized system of both hardware and software, like a central nervous system. BAS provides lots of benefits, including the ability to control your building from anywhere and improved energy management. It automates all your heating, cooling and air flow needs with minimum interference.
Quite a lot operators, supervisors and facility managers leave the fans and pumps running continuously. This might seem like a good idea … the system works all the time and users would not complain any more. But this is not a good practice as the constant use will wear out motors, belts and pumps before their time. Maintenance cost will rise and the utility bill will rise even higher.
Like people, building systems need a break. The best way is to check how people use a building, and see if we can schedule control changes for the area. If an area is only used some of the time, say during business hours, we know we can power down HVAC units after hours.
We have to make sure the unit could be turned on when needed. For example, if the air handling unit is set to unoccupied mode, it does not supply any conditioned air to the space, but it will restart when the space temperature drops below the unoccupied heating setpoint or unoccupied cooling setpoint. Only when there is a good backup plan can users feel comfortable and support these energy-saving scheduling initiatives.
With schedule control, devices will run for less time. Usually we can turn it off over the weekend. Even if we need to run the unit 12 hours a day, from 7am to 7pm, we could still save 65% on the electricity of the motor. The savings grow when we factor in gas for heating or electricity for cooling.
Below is a simple trend chart for a unit.
As the unit was running continuously before, the electricity consumption was 170,792KWh annually.
After we implemented a weekday schedule, the power consumption dropped to 60,830 KWh. The users did not feel any difference.
Schedule control on an HVAC device is a straightforward and most efficient way to save energy. It could also extend lifetime of the equipment itself. That’s saving 2 ways … a real no-brainer.
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