Is the building ready for the week it goes below twenty?

Where the building stands

Everything on the list is ticked. That is rarer than you would think. The thing to do now is put a date in the diary to check it again next October, because every one of these drifts.

1. Test the freeze protection on water and steam coils. A capillary stat that has never been tripped is an assumption, not a protection. It is a ten-minute test per coil and it is the single item on this list most likely to cost you a building.
2. Walk the pipework in unheated spaces. Insulation that has fallen off, trace heating on a circuit somebody switched off at the panel, a pump in a corner nobody looks at. Do this before the forecast rather than during it.
3. Start every unit heater now. A gas heater that has sat unused since March will fail on the first cold morning, not on a mild afternoon in October when somebody could fix it easily.
4. Check the outdoor air dampers actually close. A damper stuck part open pulls outside air across coils all night. It is also one of the commonest reasons a building will not hold temperature during a snap.
5. Review the setback schedules. Saving energy at night is sensible until the setback is deep enough that a corner of the building reaches freezing. Set a floor, in writing, and tell whoever holds the controls.
6. Get a low-temperature alarm that reaches a person. The difference between a nuisance and a flood is usually whether somebody found out at 2am or at 8am. This is the cheapest item here.
7. Deal with condensate in unheated voids. A frozen trap backs water into a unit and out through a ceiling. Either protect the run or drain it down for the season.
8. Make sure somebody on site knows where the valves are. Print it, laminate it, put it on the plant room door. During a burst nobody is going to find a drawing.

Rarely below 30°F: your exposure is mostly the one unusual week rather than the season. That makes the alarm and the freeze stats matter more than insulation does — you want to hear about a problem, because the building will not be sitting at risk all winter.

A few nights below 25°F: this is the range where the cheap items pay for themselves. Dampers, setback floors and a working alarm will cover most of what actually happens to buildings around here.

Hard freezes below 20°F: treat the pipework and the coil protection as the priority rather than the controls. At that temperature an unprotected run in an unheated void is a matter of hours, not days.