Most of the existing codes have focused on the amount of air you need to exhaust to carry all the smoke, grease and odors out of the kitchen. Back when many of the building and mechanical codes were first written, that entailed a lot of educated guesswork, resulting in what many have long believed are exhaust volumes way beyond what’s actually needed. Using UL-listed equipment has helped operators get around some of these generous margins of error. UL, though, tests equipment for safety, not performance.

Much of the testing that led to ASHRAE 154P foc-used on how much effluent is produced by each type of cooking equipment under different load conditions. With more precise measurements of how much air has to be moved to carry away effluent for each piece of equipment, it becomes easier to spec an exhaust system based on the equipment that’s in the kitchen.