The latest trend in chiller plant design is to use eye-catching enclosures, often glass boxes, that allow mechanical systems to be visible from outside. However, this can interfere with the cooling of the chiller plant. The designers of The Ohio State University chiller plant came up with an alternative solution.
The new 10-story plant uses precast concrete panels with a series of openings that allow a view inside while keeping the interior temperature consistent and the energy use regulated. Precast concrete also enabled the designers to stay within the tight budget.
"The sloped surfaces and various openings could only be designed by using precast concrete without adding significant cost and time to the project," says Eric Martin, principal at Ross Barney Architects.
The designers developed 11 different panel types, which allowed for the reuse of the forms to create the more than 200 panels required for the project. By changing the orientation of the panels, they were able to create a more dynamic facade while avoiding the added cost and complexity of additional formliners.
The precast concrete panels feature a high-polish finish and are embedded with fins of diachronic glass that cast rays of colored light across the concrete surface. The result is a facade that changes with the time of day, season, and location of the observer.
"The design team decided to polish the exposed surface of the concrete, not only to reduce the potential of stains and dirt from collecting on the surface, but to enhance the colors from the glass fins that protrude from the building facade," Martin says.
Prior to construction, High Concrete worked with the building team to create highly detailed three-dimensional models of the structure to identify and resolve conflicts between the structural steel and precast concrete cladding that is suspended from it. They also produced several mockups of the panels to ensure that the sheen of the polished concrete met with expectations.
The glass sections are attached via brackets that fit into specific slots on the edge of the precast concrete panels. To avoid increasing the joint width and accommodate the movement between the panels and the thickness of the stainless steel plates for the brackets, the edges of the panels were notched to receive the fin's brackets.
Precast concrete also helped the team meet a very tight schedule. The design team chose the largest panels possible to accelerate installation. The main panels are 9 × 30 ft (3 × 9 m) with 35 ft (11 m) tall top panels that enclose the cooling towers. More than 100 of the connection attachments were attached to the structural steel frame as it was fabricated, saving time during erection, Martin says. "The speed in which precast concrete panels can be installed was another reason why the material was chosen."