MAU is the abbreviation for makeup air unit, a mechanical ventilation system that supplies conditioned fresh outside air to replace exhausted indoor air in buildings. The acronym is widely used in HVAC design documents, specifications, and facility management to reference these essential air-handling devices. MAU systems are critical components in commercial kitchens, laboratories, and industrial facilities requiring dedicated exhaust ventilation.
Functional Purpose and Design
MAU systems prevent negative pressure created by exhaust fans by supplying filtered, temperature-controlled outside air into occupied spaces. Units are equipped with outdoor air intakes, filters rated MERV 7 to MERV 13, heating and cooling coils, and variable-speed fans. Supply air volume typically matches or slightly exceeds the building’s total exhaust CFM to maintain neutral or slightly positive pressure. Integration with building management systems allows automatic damper control and demand-based operation.
Installation and Maintenance
MAU placement requires outdoor air intakes positioned away from exhaust stacks, loading docks, and pollution sources per ASHRAE 62.1 standards. Maintenance includes monthly filter inspections, quarterly coil cleaning, and annual professional servicing to ensure optimal performance. Proper MAU operation reduces energy costs, improves indoor air quality, and extends the life of exhaust systems by preventing imbalanced airflow.