MEP Engineering · Engineering Glossary
Make-up air (MUA) is supply air introduced into a space to replace air that has been exhausted, maintaining neutral or slightly positive pressure in the building. Without adequate make-up air, exhaust systems draw inadequate airflow, create negative pressure problems, and can cause back-drafting of combustion appliances.
In commercial kitchens, large volumes of air exhausted through the grease hood must be replaced by a make-up air unit, which may supply heated, cooled, or unconditioned outside air depending on the climate and owner's preference. The mechanical engineer balances the exhaust and supply quantities, determines where make-up air should be introduced (short-circuit protection is important in kitchens), and selects equipment accordingly. In lab and healthcare environments, 100% outside air systems require equal make-up air. ASHRAE 62.1 and the IMC specify how make-up air must be distributed to avoid thermal discomfort or short-circuiting. Apex Grid designs make-up air systems for restaurants, laboratories, industrial facilities, and commercial kitchens.
Apex Grid Engineering maintains this glossary as a resource for architects, contractors, developers, and property owners who encounter unfamiliar engineering terminology on their projects.
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