Abstract: The present application is directed to an environmental control system for an agricultural animal housing facility. This system includes a plurality of air handling systems configured to deliver supply air to an agricultural animal housing facility, wherein each air handling system is configured to receive a portion of fresh air and a portion of recirculated internal air, and wherein each air handling system is configured to mix the fresh air and internal air and provide the resultant mixture to the agricultural animal housing facility as supply air. The plurality of air handling systems are configured to regulate a proportion of fresh air to internal air in response to an internal temperature of the agricultural animal housing facility.