Getting Kitchen Hood Exhaust and Makeup Air Right

For general contractors, engineers, and building owners, getting kitchen ventilation right means fewer callbacks, better building performance, and a safer facility.

Every Cubic Foot of Air Matters

A kitchen exhaust hood removes heat, grease, smoke, and steam—but every cubic foot of air it exhausts must be replaced with makeup air. Too little makeup air creates negative pressure, pulling conditioned air from the dining room and outside air through the building. Too much makeup air can reduce hood performance, allowing smoke and grease to escape. Proper balance is essential. An unbalanced kitchen can cause:

• Smoke and cooking odors in the dining room

• Doors that are hard to open or won't close properly

• Higher energy costs

• Poor occupant comfort

• Grease buildup in ductwork

• Failed inspections

• Increased fire risk

Designing the Right Airflow

The International Mechanical Code (IMC) establishes minimum exhaust rates based on hood type and cooking equipment.

Typical design airflow ranges include:

For example, an 18-foot Type I hood serving heavy-duty cooking equipment may require approximately 7,200 CFM of exhaust. Proper duct velocity, grease filters, fire suppression, and hood selection are equally important to ensure grease is captured and safely removed from the building.

(Important Note: Demand-Controlled Kitchen Ventilation (DCKV) systems automatically adjust fan speeds based on cooking activity, often reducing kitchen ventilation energy use by 30–50% compared to constant-volume systems.)_

Balancing Makes the Difference

Design calculations are only the starting point. Once installed, the system must be tested and balanced to verify exhaust and makeup air match actual operating conditions.

A qualified Testing, Adjusting, and Balancing (TAB) contractor verifies:

• Exhaust airflow meets design requirements

• Makeup air is properly matched

• Hood capture is effective

• Building pressure remains stable

• The kitchen stays slightly negative to adjacent dining areas, preventing odors and smoke from migrating into occupied spaces

The Bottom Line

A kitchen exhaust system is only as good as its balance. Proper Testing, Adjusting, and Balancing ensures the exhaust hood captures what it should, makeup air replaces what is removed, and the entire building performs safely and efficiently. When exhaust and makeup air work together, everyone benefits—from the cooks in the kitchen to the guests in the dining room.