Ventilation Systems: A Breath of Fresh Air
By pulling out smoky air and pumping in clean air, proper ventilation keeps restaurants comfortable and safe.
By Lisa Bertagnoli, Special to R&I -- Restaurants & Institutions, 11/1/2007
Restaurant ventilation, both whole-house and for heat- and vapor-producing equipment, exists for three reasons: to help prevent fires, given that accumulated airborne grease particles in kitchens can catch fire; to improve customer comfort, because ventilation removes cooking odors from the air; and to ensure employee comfort, because proper ventilation helps keep kitchens cool.
In recognition of these concerns, most municipalities have adopted NFPA 96, ventilation standards established by the Quincy, Mass.-based National Fire Protection Association. NFPA 96 specifies that the front of the house, the back of the house and any piece of equipment that produces smoke or grease-laden vapors be vented. The standards also call for the delivery of adequate return or makeup air (fresh air pulled in to replace the hot or greasy air exhausted out) so as not to create significant negative pressure, which can pose a fire hazard.
Ventilation News
Most restaurants comply with the standards using simple systems: HVAC systems plus hoods over cooking equipment and ducts that vent air out the roof or the side of the building (different municipalities have different requirements).
One advancement in ventilation is the use of ultraviolet lamps in exhaust hoods: Ultraviolet light creates a chemical reaction that turns grease particles into a gray ash—a compound less volatile than grease. The process significantly reduces grease odors and keeps ductwork cleaner for longer. That makes it ideal for operations that have large, complex ventilation systems (say, through the roof of a high-rise), says Tony Spata, director of environmental services for Chipman Adams, a Park Ridge, Ill.-based architectural firm.
The system, which migrated to the United States from Europe about two years ago, is very expensive; the payback comes in the form of lower cleaning bills for the ductwork.
Another newer development is "demand-control ventilation," through which ventilation systems are regulated according to how much heat a kitchen is producing. More heat during busy periods means more fresh air; less heat during down times means less return air. Such systems "keep the kitchen more comfortable and reduce energy use," Spata says.
Overall, he says, operators, realizing that kitchen air and dining-room air mingle, are integrating front- and back-of-the-house ventilation systems. The systems work in tandem to keep temperatures controlled in the front of the house and smoke and grease exhausted in the back of the house.
To Smell or Not to Smell
That leads to the age-old ventilation dilemma: At what point do pleasant cooking aromas become annoying cooking odors?
Daniel Orr, chef-owner of Farm Bloomington, a 10,000-square-foot restaurant complex scheduled to open Dec. 1 in Bloomington, Ind., installed several types of ventilation to meet local code. Farm Bloomington has ventilation over the cooking island to remove grease-laden heat, over the pizza oven to remove dry heat and in the dishroom to remove wet heat.
Orr also had to ventilate through the top of the building and keep the exhaust 15 feet away from other buildings. In sum, the special ventilation added $40,000 to the cost of construction.
All of that ventilation, however, will not totally remove from the restaurant the smell of freshly prepared food. For instance, in the 60-seat area for the Market, which will serve coffee and baked goods, Orr wants customers to smell the "dry" aromas of, for example, fresh-baked cinnamon rolls. The rolls will bake in electric convection ovens and will "perfume the whole space," Orr says.
And in the 85-seat casual-upscale Farm restaurant, Orr wants customers to smell the local ingredients he’s cooking. "There should be some smell of food," he says. An aroma-free environment, he adds, is more suited to very expensive restaurants.
Farm Bloomington looks for a happy middle ground. "If it’s to the extreme that customers’ clothes smell like food, that’s probably a bad ventilation job," Orr says. "We’re trying to create an ambience where there are aromas, but not clingy, oil-based aromas."
Heavy Users
Ventilation, to some extent, depends on the menu. For instance, Wingstop, based in Richardson, Texas, relies almost completely on fryers to produce its menu of chicken wings. Each of the chain’s 315 restaurants has five fryers; above the fryers is a canopy-style hood that has an exhaust fan and a makeup-air fan.
Wingstop restaurants exhaust 2,200 cubic feet of air per minute and return 1,760 cubic feet, says John McDonald, vice president of construction for Wingstop. That’s an 80% rate—one that McDonald says meets the fire code and keeps the kitchen and the dining room comfortable for employees.
Doug Dunlay, who with his business partners owns six Chicago-area restaurants, installed special ventilation in two operations: Frasca Pizzeria & Wine Bar, which has a wood-burning pizza oven, and Smoke Daddy, which has a barbecue/smoker.
At Frasca, the wood-burning oven has its own hood because of a Chicago ordinance that requires restaurants to vent "live fuel" equipment separately from grease-producing equipment. At Smoke Daddy, the barbecue/smoker is vented separately with two vents. Still, "When you walk in, it smells like smoking meat," Dunlay says.
To help control the smoke scent, Dunlay has installed an industrial smoke-eater above the entrance to the kitchen. That way, customers can experience the aroma of the restaurant without having their clothes smell like a campfire when they leave.
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