Serving up Change in School Cafeterias (with related video)
Jul 1, 2011 12:00 PM, By Mike A. Capalbo
The top five challenges and solutions for education institutions that are upgrading kitchens.
The Pennsylvania Avenue Residence (PAR) dining hall at the University of Illinois at Urbana-Champaign has a new look and feel that appeals to the 21st-century student. Architect: DeStefano Partners. Photo by Barbara Karant/ Karant + Associates, Inc.
This isn’t your grandfather’s cafeteria. No sterile white walls, institutional smell or Sloppy Joes in sight. Instead, today’s education institution kitchens are colorful and inviting, designed with curvature and stainless steel to compete with local restaurants, offering more variety and efficiency to the demanding health-conscious "Generation Me" consumer who is short on time and big on selection. In short, campus eateries are less "cafeteria" and more "cafe."
Unlike their predecessors, these cafes imitate a mall food court and are in business for business’ sake; multiple food stations include different ethnic cuisines and offer transparency. The food is made in front of the consumer, and the kitchen is in the middle of the space instead of being placed in the back of the house.
These cafes have become meeting places where students gather to study and eat. They often close as late as midnight and open as early as 5 a.m., and some even service their students 24-7. To accommodate these new demands and still meet rising energy efficiency and operational budget requirements, cafeteria HVAC systems have gotten a facelift, too.
With more efficient equipment and controls, the mechanical support for university kitchens now can meet comfort, safety, energy conservation and budget demands. Innovations in technology and engineering have transformed the challenges of yesterday’s school kitchens into the solutions of today’s sustainable and economical college cafes.
Taking the challenge
The top five challenges and solutions to kitchen upgrades in education institutions:
1. Comfort Considerations.
-Challenge: Yesterday’s cafeterias were designed to deliver conditioned air only to the dining hall space, then repurpose it as makeup air to be transferred into the kitchen through ceiling vents. This transfer air could be as hot as 80°F when entering the kitchen. As a result, air temperatures as high as 100ºF may be seen at the hoods where workers operate. As temperatures elevate within the kitchen, worker productivity plummets. According to a 1996 study, "Enhancing Productivity While Reducing Energy Use in Buildings" by David P. Wyon, International Centre for Indoor Environment & Energy, Technical University of Denmark, thermal comfort and worker productivity are linked; productivity may decrease as much as 30 percent in rooms with air temperatures of 90ºF and above.
-Solution: Conditioned supply air between 55º and 65ºF should be injected directly into the kitchen, so that the room can maintain average temperatures of 75º to 80ºF. Kitchens are good sites for displacement ventilation, which in this case, will supply low-velocity conditioned air about 5 feet away from the hoods via ceiling perimeter diffusers. As the cool air begins to heat, natural buoyancy will enable the hottest air to occupy the top of the space, causing intentional stratification. This upper level of hot air will then be exhausted through the kitchen hoods.
2. Hood Safety.
-Challenge: Smoke and heat control. Often in cafeterias, hood selection optimization is overlooked. Selecting the proper hood size is crucial to controlling smoke and containing heat. When a grill is not positioned properly under its associated hood, smoke can "roll out" of the hood exhaust area and consequently set off smoke alarms. Exhausting too much or too little air will create less than optimal conditions. Smoke may be visible, but heat is not. Owners often do not realize the harm done by heat rollout, including making occupants quite uncomfortable.
-Solution: Designers should review hood manufacturer information, as well as the American Society of Heating, Refrigerating and Air-Conditioning Engineers handbooks for equipment guidelines (www.ashrae.org). The proper amount of exhaust airflow must match the requirements for the cooking equipment situated under the hood. Airflow verification with a test and balance procedure should be performed during a project’s commissioning process to solidify hood safety.
-Tips: Check in with the kitchen designer periodically throughout design to make sure kitchen equipment needs haven’t changed drastically. Include hood size and exhaust air in the discussion. Hoods should overhang grills by a minimum of 18 inches.
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