In lower Manhattan, an old masonry building (which shall remain nameless) has such high thermal loads from its mechanical systems and human occupants that the air conditioning kicks on all year long—even in winter. It’s a not-uncommon phenomenon in New York and other places where masonry and early curtainwall buildings have new uses and mechanical loads but not new building envelopes. Maybe preventing heat loss in the winter is not always such a good thing?
Up to this point, conventional wisdom has dictated that achieving high thermal performance was mostly about preventing heat transfer. But, to a growing number of researchers, it may have more to do with harnessing the power of that thermal energy and ensuring that it can adapt to current and changing conditions. “You don’t want to prevent the transfer of energy,” says Jason Oliver Vollen, who is a principal in high-performance business engineering at AECOM as well as a research scientist at CASE, the Center for Architecture, Science, and Ecology at Rensselaer Polytechnic Institute in Troy, N.Y. “But,” he continues, “you want to manage it and use it to your advantage.”
Vollen is now in the third phase of an ongoing research project examining how high-performance materials can help buildings leverage the thermal energy that the sun broadcasts, instead of seeking protection from it the way most buildings do. It is one of three current projects advancing thermal performance recently funded by the AIA’s Upjohn Research Initiative grant program.
It is common knowledge that certain building materials can contribute greatly to heat transfer and overall thermal performance, affecting a building’s energy efficiency and the comfort of its occupants. What is less certain is the extent to which this kind of heat transfer impacts energy efficiency and undermines other efforts to create optimal conditions. In one example, considerable industry attention has been paid to the R-value of windows and protecting against solar gain, but relatively little information has been gathered about building-envelope performance. These three Upjohn grant research projects seek to advance that discussion in meaningful new ways.
In addition to Vollen’s project, the other two projects deal with mechanized, or “kinetic,” façades and the mitigation of heat loss through thermal bridging (which refers to the pathways of heat transfer and loss in poorly insulated buildings, such as those with concrete or metal). “It’s incredibly important that the AIA is supporting advances in these subjects,” says Drake Wauters, AIA, 2014 chair of the AIA’s Knowledge Community on Technical Design and Building Performance, and the technical director and an associate principal at Perkins+Will. “Issues of thermal performance are very important, especially in a high-performance building—because small things can make a huge difference as building performance is elevated.”
In his project, which won an Upjohn grant in 2010, Vollen is working with a ceramic tile manufacturer, Tegula Tile, in Rensselaer, N.Y., on a system of modular ceramic masonry curtainwalls that absorb the sun’s heat and then redistribute it to the rest of the building, effectively turning the structure into an energy transfer station. While plants and animals have adapted to take advantage of local climatic conditions, architects have created a building environment that often seeks to protect against climatic conditions in what Vollen calls an “antagonistic way.”
Vollen calls his project Climate Camouflage. “Just as an animal would blend into its surroundings to hide from a predator,” he says, “we’re going to make our building as invisible as possible to the climate.” The project’s masonry system uses color, texture, and morphology to balance thermal energy across a façade by taking advantage of temperature differentials, material properties, and fabrication processes that vary depending on localized environmental conditions. Using ceramic is beneficial, he adds, because it’s abundant, recyclable, and formable, and can be used in diverse applications without degradation. The system may soon be put to a real-world test: Tegula Tile and CASE are now working with the Schodack Central School District in upstate New York to do a possible pilot run of the masonry system as soon as next year.
Picking up on the idea of making buildings “invisible” or “transparent” to their environments, Kyoung-Hee Kim, an assistant professor of architecture at the University of North Carolina at Charlotte and a senior consultant at Front, received an Upjohn grant in 2013 for her project “Sustainable Transparency: Kinetic Building Façades.” The project’s goals are to establish design guidelines for mechanized façades using life cycle assessment techniques to create a commercially viable prototype of such a system using these guidelines.
The project recognizes that a major issue with mechanized façades is balancing aesthetics, functionality, cost, and energy efficiency, according to Kim. As part of her research, Kim studied buildings that have kinetic façades, including the Arab World Institute in Paris; Q1 headquarters in Essen, Germany; and the Al Bahr Towers in Abu Dhabi. Each of these employs a combination of sensors, mechanized components (actuators), a control board, and a building-management system. Building upon this, Kim has designed four kinetic façade typologies that are now being evaluated using prototyping and simulation techniques.
“I envision that the role of building façades will increase, not only providing a boundary layer between outdoor and indoor environments but also fulfilling adaptive roles in responding to dynamic environments and user needs [in existing buildings],” Kim says. She adds that she hopes that green-building checklists will continue to evolve to take into account qualitative performance issues such as user comfort, absenteeism, productivity, and well-being, all of which can be positively affected by thermal dynamics.
Yet quantitative information is also still essential to seeing and understanding thermal performance. The third Upjohn grant project—sponsored by Payette Associates in Boston and led by principal investigators Andrea Love, AIA, and Charlie Klee, AIA—is focused on determining which materials and envelope systems best mitigate thermal bridging. Building on a first-phase investigation of seven buildings designed by Payette (which meant the researchers had easy access to all the project histories and construction documents), this new project, awarded an Upjohn grant in 2012, adds eight more buildings to the portfolio. The investigators studied each building using thermal imaging, giving special attention to common transitional problem areas such as soffits and window openings as well as envelope systems such as curtainwalls, metal panels, rainscreens, and masonry. Because they could not physically alter the existing conditions of these buildings, the researchers performed computer simulations using the Lawrence Berkeley National Laboratory’s THERM program to study potential improvements.
So far, the project has shown that thermal bridges can reduce R-values by approximately 40 to 60 percent over intended levels, which is significantly more than previously available estimates. “A lot of these buildings were designed to exceed code requirements, and we found that the thermal bridging was undermining those efforts significantly,” Love says.
“The quantification was the eye-opener,” Klee adds. “We also have seen that thermal bridging becomes increasingly a factor as we do other things better and better [to achieve energy efficiency].” There is little point, for instance, in specifying state-of-the-art insulation in a building if the thermal bridges are not adequately identified and mitigated. The researchers found that continuity is key when it comes to thermal performance. The more continuous a thermal barrier, and the lower the thermal conductance of the materials selected, the better the performance.
Similarly, to mitigate thermal bridging, continuous conductive elements such as Z-girts or masonry shelf angles must be pulled out of the thermal barrier or used discontinuously to mitigate heat transfer. While many products on the market claim to be thermally broken, the analysis showed mixed results, which demonstrates the importance of rigorous quantitative evaluation of proposed façade details.
All of the researchers hope to share the results of their projects at upcoming conferences and in industry publications, and it’s likely that the industry will see more research of this kind. “People are trying to get to a higher level of discussion and clarity and, hopefully, truthfulness in understanding the complete picture of sustainability,” Wauters says. “The architecture, engineering, construction, and ownership industries are trying to connect all the dots. That’s always a work in progress.”