Parking Garage Exhaust Systems

Underground parking garages have been in use since the first office tower and condominium were constructed. No one would want an office or residential space below grade and the builders have to dig deep to acquire solid footings for the structure, so it only made sense to turn the extra depth into useable space. Parking spaces in these garages can easily cost over $10,000.00 at the time of purchasing a condo or rent for as much as $4.00 for a ½ hour stay (Loblaws on Carlton Street, Toronto). There are no windows below grade for ventilation of the exhaust fumes from automobile traffic and this could pose a serious problem for residents. To solve this problem, large concrete shafts are constructed from the lowest level to grade level to permit air to be both exhausted and introduced back into the space. Each level of the garage will have multiple exhaust fans measuring up to 60” in diameter to propel air up the shaft to the atmosphere. On the opposite side of the building there will be the intake shaft to replace the air that was exhausted. In older buildings the fans could be operating 24 hours a day wasting a ton of electrical energy, creating a lot of noise and wear and tear on the equipment. Some buildings were updated to include time clocks to cycle the exhaust fans off at non-peak hours. Each one of these fans can exhaust up to 10,000 cubic feet of air every minute they are in use and the outside air that replaces this air is not filtered or conditioned. The large volume of air that is removed and introduced makes it impractical to heat a garage area.New building codes require the addition of gaseous sensors that will initiate exhaust fans and intake dampers ONLY as required and needed. The sensors will be mounted on columns in the garage space approximately 5 feet above the floor and sense levels of carbon monoxide in the air. At a preset recommended concentration level the CO monitor will start the exhaust fan for the area of the garage that is affected and also open motorized fresh air dampers for the introduction of fresh air. Should the CO levels continue to increase due to a failure of a fan or excessive traffic flow the system will go into alarm mode and can signal building security or the management office for investigation. This method saves massive amounts of energy and the related hydro costs. The intake and exhaust shafts are notorious for collecting everything from leaves and cigarette butts to garbage. They should be inspected on a regular basis and cleaned as required. The exhaust fans require frequent replacement of the fan belts and lubrication of the automatic back draft dampers. The screen mesh that protects the owners from coming into contact with the fan blades should be vacuumed on a regular basis and washed annually.