Most of us probably are familiar with air curtains (or air doors, as they sometimes are called). According to ASHRAE, an air curtain is a “continuous broad stream of air circulated across a doorway of a conditioned space.” Patented by Theophilus Van Kemmel (best known as the inventor of the revolving door) in 1904, air curtains most commonly are used to contain conditioned—heated or cooled—air in a space and prevent the infiltration (or, in the case of Butterfly World in Coconut Creek, Fla., exfiltration) of flying insects. That’s why you’ll see them in refrigerated warehouses and restaurant back-of-house areas, as well as on retail-store entrances. I have been recommending them to clients for several years and seen simple payback periods ranging from 10 months to 2.5 years.
Recently, a company in Sarasota, Fla.—Cool Flow Dynamics—with funding from the Florida Institute for the Commercialization of Public Research and technologies licensed by the University of Florida, devised an “air curtain” for open-case coolers used in food and beverage stores. According to the company, an average of 75 percent of the energy used to perform that type of refrigeration is wasted, and until now, the most common solution was night curtains (which obviously don’t help in a 24/7 operation). Cool Flow Dynamics’ solution is a device that uses extremely low-power plasma to create a high-velocity air stream without the need for fans or motors.
According to the institute, open-case refrigeration is the largest source of wasted energy in the U.S. retail sector, responsible for up to 55 percent of a convenience, food, or beverage store’s total energy consumption. Even in the small (approximately 3,000 sq ft) convenience-store new-construction project on which I worked recently, which will have high-efficiency closed-case refrigeration equipment, beverage cooling will account for approximately 7 percent of the building’s electric energy consumption. Coupling the Cool Flow Dynamics technology for open-case coolers with existing solutions for glass-front coolers, such as the CoolerMiser system, has the potential to significantly reduce a food or beverage retailer’s energy consumption. CoolerMiser, unlike the Cool Flow Dynamics technology, uses passive infrared sensors to power down a cooler (or bank of coolers) when the surrounding area is vacant and—by monitoring space ambient temperature, product load, and customer activity—restart the cooler(s) to maintain optimum product temperature.
By the way, the manufacturer of CoolerMiser also makes VendingMiser, a similar technology for cold-beverage vending machines in variable-occupancy areas. I also have recommended that as an energy-conservation measure. Coincidentally, the Florida distributor is—like Cool Flow Dynamics—located on the west coast of Florida. With our climate, it should come as no surprise that Florida researchers and entrepreneurs are looking for innovative cooling solutions, both comfort and commercial.