Make-Up Air

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Make-Up Air

What is Make-Up Air?

Fresh outdoor air intentionally introduced into a building to replace exhausted air, maintaining proper air pressure and indoor air quality in HVAC systems.

Description

Make-up air is fresh outdoor air that is intentionally introduced into a building to replace air that has been exhausted by ventilation systems, maintaining proper air pressure and indoor air quality. This essential component of HVAC systems ensures that buildings maintain balanced air pressure while providing adequate fresh air for occupants. Make-up air systems are critical for building performance, energy efficiency, and occupant health and comfort.

The primary purposes include replacing air exhausted by ventilation systems, maintaining proper building air pressure balance, preventing negative pressure problems, ensuring adequate fresh air for occupants, supporting combustion appliances with required air, meeting building code ventilation requirements, and improving indoor air quality and occupant comfort.

Types and systems involve dedicated make-up air units, integrated HVAC systems, passive make-up air, and demand-controlled systems for different building applications.

Dedicated make-up air units include standalone systems designed specifically to provide conditioned outdoor air to buildings.

FAQs

  • What is make-up air?

    Make-up air is fresh outdoor air intentionally introduced into a building to replace air that has been exhausted by ventilation systems.

  • Why is make-up air important?

    Make-up air maintains proper building pressure, prevents infiltration problems, ensures adequate fresh air, and supports proper HVAC operation.

  • When is make-up air required?

    Make-up air is typically required when exhaust systems remove significant amounts of air, especially in commercial kitchens and industrial facilities.

  • How is make-up air conditioned?

    Make-up air is typically heated, cooled, filtered, and humidity-controlled to match indoor conditions and maintain comfort.

  • What problems occur without adequate make-up air?

    Problems include negative building pressure, infiltration, comfort issues, increased energy costs, and potential safety hazards.

  • How much make-up air is needed?

    Make-up air quantity should generally equal or slightly exceed the amount of air being exhausted from the building.

  • Can make-up air systems save energy?

    Yes, with heat recovery, economizers, and efficient controls, make-up air systems can be designed for energy efficiency.

Fun Fact

Fun Fact: The concept of make-up air became important in the 1970s during the energy crisis when buildings became more airtight! Modern make-up air systems can recover up to 80% of the energy from exhaust air. Some systems use geothermal energy to pre-condition make-up air. Interestingly, without proper make-up air, a large commercial kitchen exhaust system can create enough negative pressure to make doors difficult to open!

CSI Code

23 37 00

NAHB Code

2300