A version of this article was first published in Nation's Restaurant News.
Given today’s high construction costs and scarcity of available real estate, restaurant companies are more likely to move into nontraditional spaces—a trend that, believe it or not, can translate into hotter kitchens.
It is a potential problem because uncomfortable kitchens can cause higher turnover among line cooks, not to mention bigger energy bills.
Those nontraditional spaces—such as a former retail box at a strip shopping center or a second-gen space on the ground floor of a multistory building—can create HVAC design challenges in the kitchens. This is especially true if multiple exhaust hoods are called for in the design.
The challenge with older buildings
Engineers overseeing a restaurant’s HVAC design need to be able to dial-in the HVAC system for positive building pressure (i.e., the air on the inside of the space transferring through building openings to the outside).
The air exhausted by hoods must be made up for (per code requirement) with replacement air brought in from outside. But exactly how to go about conditioning that replacement air is an important design decision. Handle it improperly—or not at all—and the restaurant will become an energy hog that is exceedingly difficult to cool. (Imagine cranking your home’s AC while keeping all the doors and windows wide open.)
When working on new restaurants (as opposed to older, nontraditional spaces like vacant retail boxes or ground-floor square footage at mixed-use properties), Architecture and engineering (AE) teams can easily allocate square footage and other infrastructure for Dedicated Outdoor Air Systems (DOAS). This equipment allows restaurants to maintain positive pressure and also condition outside air as it is being pulled into the building.
HVAC equipment upgrades also are possible at many existing restaurant buildings. Having zeroed-in on kitchen comfort, for example, two national chicken chains have tasked their A+E teams with finding opportunities to replace rooftop units with DOAS systems, allowing them to condition outside air and make kitchen employees more comfortable. Another fast-expanding ghost kitchen, having prioritized the comfort of its line cooks, is systematically reviewing its portfolio to better understand how its kitchens are functioning. The goal is to create criteria for avoiding discomfort and other issues in the future.
In the case of nontraditional spaces where HVAC design is more challenging, it might be necessary to find workarounds to more traditional HVAC systems. One fine-dining concept in Houston needed to ventilate five exhaust hoods in a single ground-floor kitchen. Fortunately, the multistory building had rooftop chases that made this possible, though it was a tight squeeze. The design utilized multiple louvers on the first floor to bring in make-up air.
In New England, a new restaurant lessee in a multistory building discovered too late that all the chases to the roof had been taken by other food-and-beverage concepts. It had to find an efficient way to both exhaust the hood and bring in make-up air from outside.
The solution was to use self-scrubbers to filter and exhaust the air, smells and grease from the exhaust hood out onto the street at a height of about 11 feet. In addition to being quite heavy, this equipment necessitates frequent filter changes. The design team created a mezzanine to support the weight of both the equipment and maintenance personnel and to provide quick-and-easy access. A large louver above the restaurant’s glass storefront allows air to be pulled into the space by the makeup-air unit.
Coordinate early to dial-in kitchen comfort
As one QSR operator noted, “Nobody wants to work in a hot kitchen.” Higher turnover caused in part by uncomfortable conditions on the hot line can translate into problematically short-staffed restaurants. This, in turn, can contribute to longer wait times, more fumbled orders, shorter tempers and a general degradation in the guest experience.
But not all restaurant companies are focused on kitchen comfort. It is not unusual to encounter HVAC designs for brand-new QSR and fast-casual locations that fail to condition outside air.
Those who do want to make this a priority should consult with their architecture and design team as early in the site-selection process as possible. The goal should be to fully understand what will be required to achieve kitchen comfort before signing the letter-of-intent and lease and moving forward with buildout.
This can help you get a running start on other mechanical, electrical and plumbing challenges that could occur at existing restaurant locations. That could include controlling noise and smells at ground-floor locations in multistory residential buildings, or taking into account the effect of low ceilings (more common in older buildings) on HVAC register velocities. No diner wants a blast of cold air rapidly cooling their plate of spaghetti.
The sharper focus on kitchen comfort by some chains highlights the reality that the restaurant experience is shaped by more than aesthetics and interior design—HVAC design makes a real difference in the comfort, safety and efficiency of these buildings and spaces.
Give it short shrift, and your overheated kitchen staff could end up reenacting a shouting match from the Hulu TV show “The Bear.” Dial it in, and things will hum along nicely, with nobody noticing that the thermometer always hovers at a balmy 72 degrees.
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Brent Tweedy is a Vice President in charge of engineering services supporting restaurant clients at Bentonville, Arkansas-based HFA Architecture + Engineering. Brad Martsching leads the restaurant group’s mechanical, electrical and plumbing (MEP) design team, spearheading engineering services for multiple QSRs. They can be reached at brent.tweedy@hfa-ae.com and brad.martsching@hfa-ae.com.
