ACs left running after close are one of the most common and least visible losses in business premises. Nobody leaves them on deliberately; the last person out doesn’t check every room, a meeting room is forgotten, a unit keeps running in one department over the weekend.
See it first
The first step is measurement. Until you know how many units run, for how long, on which days, every estimate is either inflated or short.
- On VRF systems, indoor unit status can be read from the communication bus.
- On split ACs, an infrared controller sends commands but gets no acknowledgement; room temperature is the indirect indicator.
- On the energy side, panel- or circuit-level metering separates in-hours from after-hours consumption.
Then set rules
- Operating schedules: working hours per floor, zone or unit group, with special days defined separately.
- End-of-day shutdown: units still on at the set time are switched off, or someone is notified.
- Setpoint limits: the lowest cooling setpoint users can choose. Comfort stays; extreme settings go.
- Exceptions: server rooms, cold rooms and 24/7 areas are excluded from the rules.
Measure the result properly
Comparing the first bill after the rules against the one before is misleading: weather, occupancy and working days may all have changed. The impact is measured by comparing periods with similar outdoor conditions and usage.
A first estimate for your own site: savings potential. For measurement and rules: VRF automation.