Mercy High School

Cincinnati, Ohio

The historic Mercy High School was constructed in the early 1920s and served Cincinnati students for 100 years. To accommodate students for academic success, CMTA renovated the historic Mercy High School campus as the new Gamble Montessori. The historic campus is built on a 14-acre site with four buildings, totaling slightly over 143,200 SF. CPS inquired CMTA to completely gut, renovate, and open the Montessori facility by August of 2019. The renovation project was accomplished on a fast-track schedule in August of 2019. This historic renovation project won first place in the 2021 ASHRAE Technology Awards.

Beginning with the demolition of old mechanical, plumbing and electrical equipment, the renovated Gamble Montessori High School has new HVAC and electrical systems, 21st Century technology, new kitchen and dining spaces, and all newly renovated classroom and support spaces. Renovations included removing walls, a new state-of-the-art kitchen & dining facility for 800 students, replacing single-pane windows replaced with insulated windows, and tuckpointing exterior walls to repair the ailing building. HVAC systems were replaced with water source heat pumps connected through a two-pipe condenser water loop to new high-efficient condensing boilers and a cooling tower. Areas where rooftop units were added back, and two new dedicated outside air units with energy recovery, were added to provide ventilation for the building, which allow the ceilings to be maintained at their original 11’ to 12’ height.

A water source heat pump system with DOAS units was selected due to the system’s inherent energy efficiency, the building’s floor plan being suitable to accept the system type, and minimal visible outdoor equipment allowing the building to keep its historic character. LED lighting was added in conjunction with daylight harvesting with an average of 0.45 watts/SF, a reduction of nearly 50% under ASHRAE 90.1-2013. The building envelope was also analyzed, which led to the decision to replace the windows with insulated ones. This allowed the central heating plant capacity to be reduced by 29% and the cooling plant capacity to be reduced by 24%. CO2 based demand-controlled ventilation was implemented in the gymnasium to limit overventilation of the space. The yearly consumption of the building as predicted is 53 kBtu/SF year and is currently tracking below 50kBtu/SF year.

To meet the project’s unforgiving timeline, CMTA researched national purchasing partners, like OMNIA Partners, to streamline all purchasing and installation of significant equipment - all while bringing in a traditional General Contractor and subcontractors to install the balance of the systems. This approach also allowed the district to do the electrical infrastructure serving the mechanical equipment at the same time through the same methodology.  This approach allowed construction to start in less than six weeks from the start of design.