Mechanical Ventilation in Highrise Kitchens

An outcome of updates to the 2022 Chicago Energy Transformation code and the changes to the 2019 Chicago Mechanical Code is an interaction between their respective requirements, leading to heightened specifications for residential kitchens. These specifications extend beyond what may seem required upon a cursory review of the Mechanical Code.

Starting with the mechanical code there have been some changes made to Table 18-28-403.3 and the associated notes, regarding how ventilation is provided within enclosed and unenclosed kitchens. See the updated table and note below:

The revised table notes that kitchens with over 4% of their required area served by operable windows, 0 mechanical exhaust is required.

However, based on the 2022 City of Chicago Energy Transformation Code, Section C402, new construction buildings must comply with the fenestration system air leakage requirements, which will result in the requirement for 5 air changes per hour to not be met, so natural ventilation is not permitted to be utilized.

Based on that fact, the space must be provided with either 1.5 cfm/sq. ft or meet the requirements of Note 7. Note 7 then provides three different options for exhaust requirements resulting in four different options to meet compliance:

• 1.5 cfm/sq. ft

• 50 cfm for enclosed kitchens

• 100 cfm for vented range hoods

• 300 cfm for mechanical exhaust for unenclosed kitchens

Note that the term “enclosed kitchen” is not defined in the code, but is generally understood to be intended to mean a kitchen located within a single room, rather than as a part of other spaces. An “unenclosed kitchen” is what is typically constructed in most projects, with the kitchen space being open to other rooms and functions.

To meet the letter of the code, the mechanical system should be designed to provide one of those amounts of ventilation to the space.

We have also had projects propose an alternative to meet compliance with this code requirement. Note that this example is being offered only as a sample of what has been previously been approved, however all approvals are on a project by project basis, and do not guarantee that any other project will be allowed to follow the same requirements.

An option that has been approved is to design the kitchen as an “enclosed kitchen” within the unit, rather than a traditional “enclosed” kitchen located within a single room. Exhaust has then been provided from near the kitchen area, at continuous 50 cfm. This allows the project to meet compliance, without having to provide a kitchen hood that exhausts out of the building, or providing a large amount of exhaust tied to a switch within the unit or when the kitchen is occupied.

Please reach out to us if you have any questions about the recent changes to the codes, or about how to apply for alternative methods for meeting compliance with the codes.