Late November through New Year’s is when many commercial buildings sit partly or fully empty. Offices close for the holidays, schools go on break, and warehouses drop to a skeleton crew. It is also when the real cold starts. At O’Hare the normal low on Christmas Eve is about 22°F, and the average January low is under 19°F, according to National Weather Service normals for 1991–2020.
An empty building is the riskiest kind in winter. Nobody notices a unit that tripped off, a dock door left open, or a back room drifting toward freezing over a four-day weekend. By the time someone comes back, the damage is done.
Set It Back, Don’t Shut It Off
Unoccupied setbacks save energy and are worth using. The setback has to protect the coldest part of the building, though, not just the room where the thermostat hangs.
- Pick setbacks every space can hold — perimeter rooms, stairwells, vestibules, and loading docks lose heat faster than an interior office. Set the schedule for the coldest spot, not the average.
- Load the real holiday dates — a schedule built for a normal weekend may not cover a closure of four days or more. Program the actual closure, and the warm-up time the building needs before people return.
- Outdoor-air dampers and freezestats — outdoor-air dampers should close or go to their design minimum when the building is unoccupied. A damper stuck open on a cold night is how a coil freezes, so test the freezestat and low-limit controls on each air handler instead of assuming they work.
- Heating plant restart — boilers and heating pumps should come back on their own after a power blip. A boiler that locks out on a holiday weekend has nobody there to reset it.
- Rooftop units and unit heaters — gas heat that failed its fall check will not fix itself while the building is closed. Clear any open heating repairs before the shutdown starts.
Make Sure Someone Is Watching
A low-temperature alarm that goes to nobody does not help. Before the closure, confirm who receives the building’s temperature and equipment alarms, and that the phone number on the list will be answered over the holiday. If your controls can be checked remotely, test that from outside the building before you leave. If they cannot, plan a walk-through in the middle of any closure longer than a long weekend.
Three Moves This Month
Load the Holiday Closure Into the Schedule
Every closed day, the setback for each zone, and the warm-up time before reopening.
Test Dampers, Freezestats, and Low-Limit Alarms
On every air handler that brings in outdoor air, before the first long closure.
Put a Person on the Alarm List
Someone who will answer over the holiday. If something fails while the building is empty, call 847.498.4590 for 24/7 emergency service.
With a Maintenance Agreement, these checks are part of the fall visit, done by a dedicated technician who already knows your equipment. Either way, the time to find a stuck damper is before the doors lock, not after.