Energy-Efficient Makeup Air Units

Unless you live in paradise, delivering makeup air to most buildings is expensive. Table 1 shows the amount of work it takes to heat and cool air (based on Chicago conditions) for a standard rooftop unit (a unit that recirculates air with typical air conditioning loads) and a makeup air (MUA) unit. Note the standard unit conditions represent 400 cfm/ton (53.68 L/[s.kW]) with 80 degrees F dry bulb/67 degrees F wet bulb (26.7 degrees C dry bulb/19.4 degrees C wet bulb) return air conditions. It can be seen that a MUA unit requires more than twice the cooling and five times the heating work as a standard unit.