Halton introduces the first in a series on Best Practices in Kitchen Ventilation.
The design of the professional kitchen follows the same methodology of the industrial design process. The layout and time dependent internal loads are driven by the application of the specific restaurant and its unique food service process.
At the beginning of the process the designer defines the type and process of the operation. The space dimensioning includes the room estimates of all functional areas, such as receiving, storage, preparation, cooking and dishwashing; everything that is required to produce the menu items. The space required for each functional area of the facility is dependent upon many factors. The factors involved include:
- number of meals to be prepared
- functions and tasks to be performed
- equipment requirements
- suitable space for traffic and movement
The difference between a well performing, functional exhaust system and poor performing system is often the selection and design of the air distribution system in the kitchen. Supply air, depending upon the delivery device (type of diffuser) can be delivered to the space at a high discharge velocity. This velocity, if introduced near the cooking equipment, can impact the thermal plume in a negative manner, creating spillage from the hood system.
The method of delivery of air impacts the space in three ways: temperature, humidity and air velocity. It should be noted that if there is no air conditioning in the kitchen, the indoor temperature is always higher than the outdoor temperature. This is due to the heat loads generated in the space, and the fact that most air delivery systems pull supply air in from the roof. Temperatures there can be as much as 30-40° F higher than outside air temperatures due to radiant absorption and convective reflection of the roof materials.
In most kitchens, the majority of heat gain is from the radiant portion of the main cook line.
Convective loads should be removed with the hood system. It is critical to calculate the exhaust air flow requirements based on the heat generated from the cooking equipment. Any un-tempered supply air should be taken into account in the load calculations as the majority of this air does not move to the hood until after it impacts heat gain to the space. Deciding the design strategy has a great effect on investment costs and the energy costs of the whole building.
Next issue we explore Heat Based Design