Innovations in window glazing and coatings have increased the energy efficiency of window walls. New coatings allow the architect to use larger expanses of glass, even when designing buildings that meet stringent green building certification programs. Architect Mark Maddalina, AIA, LEED AP, and Manager of Sustainable Design at SWBR Architects in Rochester, New York sums it up when commenting on the windows used for Rochester Institute of Technology’s Golisano Institute. Maddalina says that “the windows we used, required a connection to line voltage effectively stopping all heat loss and actually radiate heat from windows into a room, allowing the project to eliminate the use of any other perimeter systems. Occupants comment that when the occupancy sensor goes on – any draft goes away. These windows are game changers. Our energy modelers referred to this as the ‘perfect’ window”.
The mission of the Rochester Institute of Technology (RIT) Golisano Institute for Sustainability is to undertake world-class education and research programs in sustainability with major foci on sustainable production, sustainable energy, sustainable mobility and ecologically friendly information technology systems. The Institute’s goals required SWBR Architects in association with Design Architect FXFOWLE and M/E Engineering, to provide an aggressively designed thermal envelope. The Institute required that the project provide significant energy savings for a building of this type – a particular challenge for a multi-story research building located in Upstate New York.
Given these goals, the team approached decision-making for the building envelope system with two overriding criteria: Optimize Energy Performance and Minimize Energy Demand.
The envelope utilized several EFCO curtain wall systems. Its primary facade system features a thermally broken curtain wall and an array of high – performance glazing types that reduce the possibility of thermal transfer. Given the size and complexity of the curtain wall, the system was unitized, or factory assembled into larger units of seven or eight glazed components each, prior to being installed in the field. This permitted improved quality control with limited field connections and limited installation time on site.
Tracking against a baseline energy model, the architectural team sought to provide no more than 40% vision glazing on the envelope and to improve upon the thermal performance of all components. They evaluated parallel energy and cost models specific to the envelope. The selected spandrel glazing incorporates 4.5” thermal insulation. Daylighting glazing primarily utilizes an advanced, 3” thick glazing with a low-density, translucent infill. The building’s vision glazing is primarily a heat-mirror film glazing with krypton gas infill, which provides triple-pane performance within a 1” product.
In addition to these high-performance products, a new and innovative glazing was utilized in areas where occupants would be seated near the curtain wall. This is a double-paned glazing product that utilizes an electric current to charge and heat an invisible metal coating on the third surface. While it offers the appearance of standard vision glazing, it is designed to achieve a room-temperature set point, effectively eliminating the expected temperature differential and associated cold downdraft along a window, improving user comfort and eliminating the need for other perimeter heat systems in the project. Within the energy model, these were termed “perfect windows”, as they become “thermally opaque” when outdoor temperatures drop below 42 degrees. The heat provided is only within the cavity on the surface of the double-pane window, so the energy required to raise its temperature is generally low and the energy is more effectively applied than in conventional perimeter systems. Similar to the building lighting systems, these windows are also tied in to room occupancy sensors.
The incorporation of this technology represents both RITs’ commitment to innovation and the Golisano Institute’s work in bringing environmentally smart and efficient technologies to market. SWBR Architects’, Maddalina comments, “True innovation is not for the faint-of-heart. While the product has had its challenges with a relatively high failure rate upon initial installation and a high first cost, the project team recognizes that this technology is potentially game-changing and, as it reaches the mainstream, could represent the future of glazing technology.”
Given this array of products within the curtain wall system, the team included air and water infiltration testing as part of the installation. The system passed with no measurable infiltration found. The project is seeking LEED® Platinum certification. The electronic power glass used on this project essentially stops all heat loss from the interior to exterior while heating the interior space of the building.