If the level of conversation about sustainability in architecture were a reasonable indicator of how green building practices are today, there would be every reason to feel confident that we are making a dent in the amount of energy our houses, offices, and schools consume each day. Architects and developers seeking LEED certification for a project have many more options—both material and technological—to draw on, and the standards themselves are getting more refined and nuanced. Being green isn’t enough to make news anymore, and for many, that’s real progress.
Familiarity can breed complacency, though, and for the architect and research scientist Anna Dyson, now is not the time to get comfortable. “If you accept the idea that we have ten or 15 years to turn around climate change before the effects become irreversible, then we’ve got to rethink everything about the way we build, including the idea of sustainability.” To that end, Dyson is leading the Center for Architecture Science and Ecology (CASE), a new venture of the Rensselaer Polytechnic Institute (RPI) and Skidmore, Owings & Merrill. The program’s goal is to develop a new generation of building systems and materials that can dramatically change a building’s performance. “To make a real difference, we need a paradigm shift. All bioclimatic resources, like wind load or solar gain, are just that—resources, not problems to be mitigated.” Dyson, her colleagues, and students believe that these forces can and should be captured and transformed in a way that makes them useable on the scale of an individual building. This approach sidesteps the problems currently faced by proposals for large wind farms in the West: Sure, you can harness the energy of wind in the Dakotas, but how do you get the electricity it generates to Chicago or Los Angeles where the demand is?
Several of the projects underway at CASE address this problem by looking at building enclosures, and ways that they can be exploited to capture and transform solar energy. One project uses small glass lenses and tiny PV cells within standard curtain wall assembly, while another is based on the idea that a fritted glass wall would be much more useful if the frit pattern could shift in density and design to accommodate changing environmental conditions. (Both are profiled below.)
The genesis of CASE was a desire to fully embed research into practice so that the architect’s practical experience could inform the kinds of questions that the researchers were asking, and vice versa. RPI did have a program in built ecology, but Dyson and the school wanted to push it further. In SOM’s Carl Galioto, they found a receptive ear. Galioto is the partner in charge of the firm’s technical group, which focuses on building science, digital design, and materials research, as well as construction documents and administration. He explained that his group is always looking for emerging applications—they were early supporters of Andrew Marsh, for example, whose analytical software was recently purchased by Autodesk and is now on the market as EcoTect—and that the collaboration is a natural one. “We don’t want to wait for the market to provide new solutions, or to work on a project-by-project basis,” he said. “We are also interested in things that aren’t yet products.” In CASE, SOM can help influence the development of these new technologies, and bring a distinctly architectural sensibility to the process. “One of the things we bring is the perspective of regular practice, and the aspirations of designers.” This squares with what Dyson and her colleague Jason Vollen believe, that if the material or product is too expensive or tough to install and maintain, it will never fly. “We want to ask questions from an architectural standpoint, not just a technical one,” said Dyson. Vollen added, “Some of these issues could be just material science problems, but they should be architectural ones, too.”
The research underway at CASE is varied in scope and level of development, but it all shares a dual desire to be firmly grounded in the realities of building while trying to push beyond the model of incremental mitigation. Dyson described three rough categories, ranging from a 5-to-10-year time frame from conception to application, all the way to the “science fiction” projects, which aren’t based on getting new products to market. Some, like the dynamic display facade system, are advanced enough that the research team has applied for preliminary patents and are working to incorporate protoypes into real projects. Even recently, the dynamic display system was scheduled to go into an upcoming SOM building in Midtown, but according to Galioto, the economic downturn has put that on hold. The recession will certainly put the brakes on a lot of projects in New York, but the researchers at CASE will use the down time well. The pace of academic research is naturally much slower than the kind that many firms practice on a building-by-building basis, so by the time that construction picks back up, CASE may have developed some tools to shift the paradigm in building ecology. It won’t be a moment too soon: “It is an absolutely critical moment for emerging economies to adopt different technologies,” said Dyson. “But those of the 21st century, not the 20th.”
all images courtesy case
Integrated Concentrating Solar Facade System
Scientists have been capturing solar energy for hundreds of years, and solar panels have been around for decades. With the advent of semiconductors and the development of photovoltaic (PV) cells, which transform captured solar energy into electricity, the race has been on to find ways to control solar energy at every level. Today, PV and Building Integrated Photovoltaic (BIPV) technologies are applied to provide electrical power, thermal energy, enhanced daylighting, and reduced solar gain technology. CASE researchers are working on a technology that will increase daylighting in a building’s interior while simultaneously reducing unwanted solar gain.
The Integrated Concentrating (IC) Solar Facade System is a completely new model with several advantages over existing daylighting systems, which have been unable to capture solar energy viably while providing diffuse daylight for interior spaces. By transferring the IC technology to a daylighting system within a “double-skin” facade, the system will remove unwanted solar gain from the building envelope before it is transmitted to the interior.
The major technological advance that underlies the idea is the miniaturization of PV modules into what they call solar-cell concentrators, which are the modules that make up an IC Solar Facade System. The modules are placed within a glass facade or atrium roof and mounted on an accurate, but inexpensive, tracking mechanism. Because the cells are so much smaller, they must track the sun’s path; therefore, they are embedded with Fresnel-type lenses, which direct and concentrate sunlight onto a smaller PV cell. Furthermore, the system is compatible with existing structural components, encasements, and maintenance procedures.
CASE’s tracking IC Solar Facade System has been demonstrated in several “proof of concept” lab-scale prototypes with multiple cell types. Phase I of this project will include testing a full-scale prototype at a new building at the Center of Excellence in Environmental and Energy Systems in Syracuse. Postoccupancy testing of this prototype will provide critical data for assessing operating constraints and developing the future transfer into distributed building systems. SH
High Performance Masonry Wall Systems
Scientists study the strategies that flora and fauna have developed to flourish in specific—and often dramatic—climatic conditions in an effort to glean information that might inform how we can better adapt to our own climates. After studying the active and passive thermal controls of barrel cacti and termite mounds, a group of CASE researchers led by Jason Vollen hope to use their findings as models for masonry-wall construction. Their proposition is that the structure of barrel cacti and the thermodynamic design of termite mounds offer models for climatically responsive building technology.
The barrel cactus of southern Arizona has one of the highest thermal tolerances of all plants and is capable of regulating its core temperature despite high diurnal temperature fluctuations. These desert succulents store water and operate as living cisterns. Stored water delivers nutrients and serves as a heat sink, absorbing and distributing thermal load. Furthermore, the barrel cactus also has an exterior layer with self-shading spines, a high surface area to circumference ratio, and a liquid thermal mass. Density, location, and the color of the spines also play a significant role in maintaining its thermal equilibrium.
Termites are not capable of regulating their internal temperatures, but they require an environment of 86º F and 80 percent humidity in order to thrive. They achieve this by building shelters, either cathedral or dome mounds, depending on where they’re located.
Cathedral mounds use convective cooling and heating in hot climates. In forests, where radiant heating is not a problem, termites build dome mounds with a thicker wall mass. Of particular interest is their ability to change mound shapes, if environmental circumstances change.
RPI researchers are developing high-performance masonry units that respond to climatic fluctuations in the same way that cacti and termite mounds do. For instance, in one case study, masonry tiles with articulated surfaces can be precisely formed for a given location so that they provide summer shade and allow winter solar gain in the same way that cactus spines do. In another study, tiles vary in thickness depending on where they’re located on the building’s exterior. Like the cathedral mounds, tiles exposed to the summer sun are thin, enabling the masonry to absorb and release heat quickly. In the dome mounds, the tile’s cone is thicker and serves as a heat sink.
Preliminary results suggest that the modulation of form, surface geometry, glazing, ventilation, and evaporative cooling can combine to maintain consistent interior temperatures. SH
Electropolymeric Dynamic Daylighting System for Windows
Glazing technology has come a long way since uninsulated, single-paned windows barely blocked the elements. Today, curtain-wall systems, especially those with glazing that is electrochromic, or responsive to an electric charge, operate with much greater energy efficiency. A limitation has always been that these systems are either on or off. Researchers at CASE are about to demonstrate how new energy display technology will provide opportunities to achieve even higher levels of geometric and spectral selectivity through Electropolymeric Dynamic Daylighting Systems (EDDS), the next generation of switchable daylighting. In short, imagine glazing in which the frit pattern can grow denser or lighter, or move to follow the angle of the sun.
The research team believes the best way to commercialize EDDS is to build a prototype multilayered, variably translucent, insulated glazing unit (IGU), which would be applicable for residential and commercial use. Prototype testing will determine to what degree the optimization of daylighting on a building’s interior will eliminate glare, reduce electricity use, and ultimately increase energy savings.
With regard to glare, existing shading devices generally can’t respond to constantly changing daylight conditions: Even though conventional louvers reduce glare, they also reduce daylight and thus increase the need for electric lighting. EDDS will provide a high level of user control over glare, while simultaneously offering up to 16 transparency options within a triple-glazed window unit. Sensors would control the level of transparency on different surfaces within the IGU, bringing a flood of diffuse sunlight into interiors, while intercepting the direct rays.
An equally important issue is heat gain. In an EDDS-based triple-glazed IGU, sensors could switch among the layers, allowing it to either shed heat gain or retain it passively. In the summer months, for instance, one polymeric layer could switch on to block infrared rays while maintaining visibility. In colder months, another layer would trap infrared rays in the window cavity to provide passive solar heating, while blocking glare.