I'm currently modeling a few buildings where the design team wants to explore the effectiveness of heat recovery on kitchen exhaust hoods.
In the DOE Commercial Reference Buildings, kitchen cooking equipment - 70% of the energy is modeled as "lost."  Some of this energy is truly "lost" to the food being cooked, but much of it is captured and exhausted by hoods. It is not mixed with the zone, but in the model, it is captured by a system and should be modeled as such.
When modeling lights and refrigeration equipment, we are given the option to specify a "return air fraction" - a portion of the heat that is transferred directly to the zone return air. It would be awesome if this option were added to the following objects:
ElectricEquipment
GasEquipment
SteamEquipment
HotWaterEquipment
OtherEquipment
It would also be great to have an "Exhaust Air Fraction" option - so that some of the heat generated could be assigned directly to the exhaust air node.
While the need to model kitchen exhaust heat recovery illuminates the limitation within EnergyPlus, it is a limitation in accurately modeling kitchen energy use even without heat recovery.
Thanks!
Karen