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By Barbara Knecht

“The temperature at the inside surface of the Active Wall is almost room temperature,” explains Bernie Gandras, a SOM partner. “There is a continuous 3-inch-tall slot at the floor line, and another 3-inch slot in the ceiling cavity. Low-velocity (4CFM PSF) air is naturally pushed through the wall and returned to the ceiling plenum for cooling.” Four-inch vertical blinds in the cavity provide solar protection and can be manipulated individually by the occupants.

 

Computer renderings by Flack + Kurtz

These kinds of systems do add first-time costs to construction, primarily in overall increases in building volume for the raised floor, or materials and installation. High energy prices in Europe and different building practices (raised floors are generally more common) have made these systems common in spite of their higher first-time costs. U.S. demands seem to be shifting rapidly toward better energy management, supported by greatly increased human comfort and reduced risk to owners and developers by using systems and methods that have been well-tested in Europe.

 

Simulation software makes the difference The international engineering firm Buro Happold has taken the power of computer analysis to great heights. Computational Simulation and Analysis (CoSA) is their multidisciplinary group of analysis specialists, which provides services for 50 to 60 percent of Happold’s projects. The expertise of the group extends from aeronautics to architecture to academia. CoSA has gathered building-simulation software to model environmental and human impacts on both the exterior and the interior surfaces and spaces of a building under one roof. For example, they can model airflow in and around a building to determine the best locations for openings, or they can model the patterns of air within a space to design the most effective heating and ventilating system. Fires can be modeled to design evacuation systems; daylighting can be simulated to reduce the need for artificial lighting; and the movement of humans can be modeled to design for safety and comfort. Computational Fluid Dynamics (CFD), used by Flack + Kurtz in the analysis and design of the underfloor air-delivery system for the Alcoa building in Pittsburgh, is widely used by CoSA, as well. Air distribution within a space is modeled using CFD to reveal drafts and stagnancy, hot and cold areas, so systems can be designed much more precisely and efficiently. All of the software used by Buro Happold—CFX or Flovent for CFD analysis, Thermal Analysis Software (TAS) for thermal modeling and system simulation, or Building Exodus for evacuation studies—is commercially available. In some cases, capacity is increased by modification of the software. “BH has taken Building Exodus software, which was originally designed for emergency evacuation only, and found ways to apply it to foot traffic in airports, train stations, and sports venues,” according to Stribling. “In cases where we are helping determine a building’s orientation, we use CFD to model building shading and sunlight. By integrating simulation analysis, the result is more likely to be an optimum design to reduce energy consumption, take advantage of passive environmental controls, and provide the highest level of human comfort. B.K.