The St. Joseph Medical Center main tower was constructed in 1978. It has 4 central air handling units that serve patient and support spaces. Hoss & Brown Engineers along with SWD designed and commissioned the replacement of AHU-3 and AHU-4 penthouse unit. These two air handling units currently serve 90,000 square feet of the hospital and we were charged with completing this project without disrupting of its operation, thus the system tie-overs to the new AHUs required a 24/7 work schedule.