Broadly speaking, a MAU, or Make-Up Air Unit, is a category of HVAC unit designed for use in commercial and industrial applications. In addition to providing high-efficiency heating, Make-Up Air Units provide necessary ventilation, pressurization, and indoor air quality benefits for a safer, more comfortable, and more efficient space.
Indoor Air Quality
An important feature of Make-up air units is the introduction of fresh air to the indoor space after air is removed by exhaust. This is a common need in commercial or industrial facilities, kitchens, warehouses, and manufacturing space, where a certain amount of air must be ventilated from the building in order to remove smoke, fumes, CO2, exhaust, and so on in order to meet indoor air quality safety regulations and code requirements. According to the World Health Organization, adequate ventilation and air exchange is important to prevent harboring bacteria, mold, and viruses that can cause disease. Thanks to COVID, there’s more awareness than ever than proper ventilation is essential to protecting the health and safety of all building occupants, guests, and workers.
While removing contaminated air is a good start, replacement air is needed in order to prevent Negative Pressure (more on that in a moment) and deliver fresh, uncontaminated air to building occupants.
Make-up Air vs. Negative Pressure
On the JK Blog, we’ve talked in the past about the importance of Building Envelope Tightness. A certain level of Building Tightness helps your HVAC system work more efficiently. However, there can be too much of a good thing. Negative air pressure occurs when the air pressure inside your space is lower than that outdoors. When the space in a home or building is ventilated and not replenished, the result is depressurization (or negative pressure). This can cause issues with poor indoor air quality, HVAC equipment running inefficiently and unevenly, poor combustion and back-drafting issues, underperforming fume extraction or dust collection, cold air infiltration in winter, and more.
This, as you might have guessed from the name, is where Make-up Air Units come in. MUA systems correct negative air pressure and help prevent these problems. As a bonus, MUA systems are highly efficient themselves and can provide these benefits without placing an undue burden on operating costs.
In temperate climates, simple ventilation fans can sometimes handle all a facility’s ventilation needs by simply introducing outdoor air. However, in Pennsylvania and in any climate that experiences cold winters or hot summers, bringing in unconditioned outdoor air can significantly affect indoor temperatures and humidity and affect the comfort and performance of occupants. Make-up air systems are an ideal solution that tempers and conditions the outside air before introducing it indoors, preventing that drop in comfort.