Align Systems With Occupancy Schedule
Facility engineers should coordinate HVAC schedules in the building automation system (BAS) with expected occupancy to optimize energy usage. Buildings that are not used at night, on weekends or for long periods of time (such as during semester breaks) should have their temperature settings adjusted. For facilities with regular occupancy schedules without a BAS, programmable thermostats make temperature setbacks a reliable option.
Reduce Ventilation During Low Occupancy
For spaces that have large swings in occupancy (such as auditoriums, gyms, classrooms and cafeterias), energy can be saved by decreasing the amount of ventilation supplied by the HVAC system during low-occupancy hours. A demand-controlled ventilation system senses the level of carbon dioxide in the return air stream, uses it as an indicator of occupancy, and decreases supply air when carbon dioxide levels are low.
Maintain A/C Economizers
Many air-conditioning systems (other than those in hot and humid climates) use a dampered vent called an economizer to reduce the need for mechanically cooled air by drawing cool outside air into the building. If the economizer isn’t regularly checked, the linkage on the damper can seize up or break. An economizer that’s stuck in the fully open position can add as much as 50 percent to a building’s annual energy bill by allowing hot air in during the air-conditioning season and cold air in during the heating season.
Maintain Rooftop A/C Units to Maximize Efficiency
On a quarterly basis (or after filters are changed), make sure the panels to your packaged rooftop air-conditioning unit are fully attached, with all screws in place and all gaskets intact so no air leaks out of the cabinet. Over the course of a year, leaking chilled air can cost $100 per rooftop unit in wasted energy.
Adjust Chillers to Load Needs
Operators often run too many chillers for a given load. Every chiller has a range of loading conditions in which it operates most efficiently. Turn chillers off to keep the remaining units operating in their most efficient zones — typically above the 30 to 50 percent load mark.
Source: Business Energy Advisor.