Putting on Airs

What's on the menu determines the type and scope of HVAC system needed

By Scott Hume, Executive Managing Editor -- Restaurants & Institutions, 12/1/2003

Flame-broiled foods and open kitchens are increasingly popular with operators and diners, but for architects and engineers both pose challenges in designing cost- and energy-efficient heating, ventilating and air-conditioning (HVAC) systems.

Open kitchens, particularly with grill-specialty menus, “are problematic. You have to balance exhaust air with a fresh-air supply or you’ll get unwanted migration [of smoke and odor]” between kitchen and dining areas, says Steve Haasl of Minneapolis architects Shea Inc., which has designed more than two dozen restaurants for New Hyde Park, N.Y.-based Morton’s of Chicago.

Open-flame grills deposit smoke and grease particles into kitchen air that need to be trapped and exhausted by hoods before they waft into dining rooms. The challenge can be in doing so without disrupting temperature or airflow in both areas of a foodservice operation.

When Bertucci’s Brick Oven Pizzeria recently was offered space on the ground floor of a new research building adjoining Children’s Hospital Boston, the Northborough, Mass.-based chain seized the opportunity. The 325-bed hospital houses a 1,500-person medical staff and 3,300 employees and is in a busy neighborhood with a large customer base.

Matching Bertucci’s needs with the space required adjustments, says Matt Dwyer, whose Leesburg, Va., engineering firm has handled systems designs for a dozen Bertucci’s units. The hospital “planned for a restaurant [in the space] but they aren’t restaurateurs,” he says.

A hood placed over cooking equipment and vented outside exhausts kitchen heat, smoke and vapors. What was available in the hospital location was an 18-inch-square ventilation shaft leading to the roof, 12 stories up. Stand-alone Bertucci’s locations normally use a 24-inch-square ventilation shaft.

Because building codes peg the size of an exhaust hood to the size of the vent shaft, kitchen design for the hospital had to be adjusted, with equipment grouped to work effectively with a smaller hood.

Available electrical power was lower voltage than typically required, but that was partially offset by tapping steam for heating water. The site also had plentiful and efficient outside-air delivery for keeping dining areas comfortable and clean, even with Bertucci’s open kitchen.

“We faced different problems than we were used to, but it all came together well,” Dwyer says.

Changes in the air Menus change in accordance with customers’ evolving tastes, with seasons and even with short-term promotions, and any such shift in what’s cooking can result in altered demands on HVAC systems. Tony Spata, the director of energy management for Columbus, Ohio-based design firm WD Partners who spent 23 years as a corporate engineer for McDonald’s Corp., stresses that HVAC capabilities must be factored into any decisions about what will be cooked and where.

“With new energy codes and greater interest in energy efficiency, the approach in design is to tailor the size of exhaust systems to the cooking operation, menu and appliances used,” he says. “If an operation designed for grilling and frying goes to charbroiling, that is a totally different kind of operation and the exhaust sytem has to reflect that style of cooking.”

Spata advises continual monitoring of HVAC effectiveness, beginning with visual checks. “Observe steam and smoke and see how well they are captured and contained,” he says. Another step is to check kitchen and dining rooms’ air balance (the amount of air supplied versus the exhaust capacity of hoods) to ensure air in both areas is properly circulated and cleaned.