Gas detection systems continuously monitor enclosed spaces for hazardous gases — most commonly carbon monoxide and nitrogen dioxide from vehicle exhaust — and automatically activate ventilation when concentrations approach unsafe levels.

Sensors are positioned throughout the space based on gas density and source location, reporting to a central controller that stages exhaust fans, triggers alarms, and logs concentration events for compliance records.

Because mechanical codes permit demand-controlled ventilation in garages equipped with detection, exhaust fans run only when gas levels require it rather than continuously — dramatically reducing fan energy while improving life safety. The same architecture extends to refrigerant monitoring in mechanical rooms under ASHRAE 15.

Gas detection is required or standard practice in parking garages, vehicle maintenance facilities, loading docks, and equipment rooms, where it functions as both a life-safety system and an energy-saving control strategy.