The Ohio State University East Regional Chilled Water Plant
Leers Weinzapfel Associates
Columbus, OH, USA
Jane Weinzapfel Andrea Leers
GBBN Architects (Architect of Record) RMF Engineering (MEPFP & Structural Engineering) Reed Hilderbrand (Landscape Architect) Olin (Campus Open Space Design)
To reduce apparent scale and to support efficient densely packed equipment layouts, two offset volumes individually respond to unique engineering requirements, while reducing building size. The interior required a large, double-height space housing six chillers and related equipment. An upper mezzanine floor with control-room flanks the chiller hall and overlooks the open activities below. A low water table allowed a full basement to further reduce building footprint. Plant safety and ease of operations and maintenance were key requirements including ease of removal and replacement of equipment in future. An interior truck driveway does double-duty in also providing the lateral “pull space’ required for cleaning the chillers at ground level. Crane movement provides access to all levels throughout the two-story chiller hall, with crane access via hatches from this level to the basement below and via hatches from the roof to ground level. Meeting sustainability objectives, the new plant is LEED Certified. The innovation of a partially cantilevered rooftop cooling tower array allowed the cooling tower screening to also shade the building on the south and most of the east and west facade (the west facade is further shaded by an existing parking garage). Digital sun/shadow modeling indicated that the effect of this screening in combination with the translucent ceramic frit on the glass did not require an additional “low-e” coating on the low iron glass resulting in an exceptionally crystalline appearance. The goal of the new plant was to significantly improve campus central plant reliability, energy efficiency and environmental air quality, and this has been achieved.
On a prominent site between campus and city, this critically important large infrastructure facility fits comfortably among its smaller academic neighbors, preserves an important green space, and frames the gateway for a new campus entry. Celebrating its function, rather than attempting to hide it, the building demanded a design that supported the campus master plan in both its unique form and underlying functional support to an expanding section of campus. The large scale structure is modulated by its composition of two offset volumes: a lower, glazed rectangular volume with semi-transparent views from the interior; and an upper lifted square volume with perforated metal walls of copper-colored aluminum. The water cooling tower enclosure provides a cost-effective envelope that also resonates in color and texture with the many nearby brick academic buildings. Metal detailing on the facade was made very sheer and smooth to emphasize the platonic sculptural volumes of the building. The perimeter of each perforated panel is secured at its bent edges to the robust steel superstructure of the rooftop cooling enclosure. The aluminum curtain-wall system is suppressed on the exterior to achieve the equally sheer and diaphanous glass volume of the base building. Both volumes are gently LED illuminated at night to provide site lighting for the surrounding pedestrian zones and to continue the dialogue between the forms and their contrasting materials. The glowing crystalline lower volume is illuminated from the inside, while the metallic volume above is illuminated by exterior ambient light.
Keeping the footprint small maintained the scale and landscape flow between buildings typical on this campus, and it kept building costs about ten percent below budget. This was done by separating and right-sizing building functions: allowing the six required rooftop cooling towers to have an independent form (100 foot by 100ft square) so as not to dictate the total size of the building (in a line these would have been almost 200’ long); and creating an efficient, linear 80 foot by 120 foot building form for the at-grade chiller hall; and providing a full basement below for pumps, water filters, etc. Made of galvanized structural steel, the cantilevered support of the cooling towers at roof level frame a new campus pedestrian street. Galvanized steel stairways, walkway gratings and equipment structural supports provide a safe and efficient rooftop workplace. Building on previous use of opaque ceramic frit, the lower, glazed volume is designed with large panels of heat-strengthened glass with three densities of translucent ceramic frit and clear glass at the columns; together these gently screen the chiller equipment within, and no artificial lighting is needed during daytime working hours. The upper screen wall is designed with two perforation densities, together with narrow open slots achieve the average 35% open area needed for equipment ventilation. The screen effectively shades the lower glazed volume. During design, repetitive material testing with basin-splash-chemicals comparing anodized aluminum, copper, and resin-coated aluminum - this found the latter superior.