There are eight natural gas fired make-up air fans and numerous hydronic unit heaters located throughout the parking garage. The make-up air fans are controlled to supply 20 deg. C supply air temperature. A CO monitoring system controls them.
Wall mounted thermostats with relatively high setpoints control the unit heaters.
The main purpose for heating a garage is to avoid freezing sprinkler and service piping. Occupancy comfort should not be a concern, as people are already dressed for outdoor conditions when they are walking from or walking to their car.
We recommend resetting the garage temperature as low as possible without freezing pipes.
We also recommend installing relays on the unit heaters to disable them when the outside air temperature is above a certain point, say 5 deg. C. The heating on the make-up air fans should also be disabled at this point.