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When Less Powers More
With energy-modeling programs and early input, mechanical engineers are increasingly involved in design decisions that are shaping the look of a new architecture
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By Russell Fortmeyer

 

Crisis as opportunity

“Designing intelligent structures is mandatory,” says Peter Tertzakian, an energy consultant and the author of the book A Thousand Barrels a Second (published by McGraw-Hill in 2006). “However, you also have to change people,” he adds. Tertzakian, whose book gauges America’s addiction to oil, doesn’t specifically address buildings as much as a culture of energy use that has avoided developing plentiful alternative energy sources to petroleum and other fossil fuels. He lays out four expectations consumers have toward energy: It must be cheap, clean, secure, and discreet (his version of NIMBYism). The change in today’s culture, Tertzakian argues, is we can no longer afford to have all four.

To take one with particular resonance for architecture, the photovoltaics on Caltrans certainly don’t qualify as inconspicuous. But photovoltaics are innocuous compared to a coal-fired power plant, and as deployed at Caltrans they represent how architects incorporate energy generation into a building without sacrificing design integrity. (For another example, see the building-integrated wind turbines of SOM’s Pearl River Tower, page 172). What PVs aren’t, however, is cheap, which explains why they are used only when required or subsidized. This argument is trotted out for every architect contemplating the use of PVs, but as Steven Strong, of Cambridge, Massachusetts–based Solar Design Consultants, says, PVs are among the few materials in buildings where owners stipulate a payback. “No one expects high design to have the payback demanded of an energy-efficient technology,” Strong says.

 

Caltrans District 7 headquarters replacement building, 2004
—Morphosis
Photography: © Rroland Halbe
The 84-kilowatt solar photovoltaic array on the south side of the Caltrans building consists of 897 panels and is designed to supply 5 percent of the building’s energy requirements. The installation was a design collaboration between Morphosis, Arup, and Atlantis Energy and was partially funded by a grant from local utility companies.

 

Architects skirt that issue by justifying unconventional design through building information models that demonstrate constructability and performance characteristics in precise, realistic terms. Once the design team sets energy performance criteria—such as beating the American Society of Heating, Refrigerating, and Air-Conditioning Engineers’ standards (ASHRAE 90.1) by 20 percent—the engineer and architect could study different curtain-wall designs by modeling them in software programs such as EnergyPlus or DOE2.

Think of the new building modeling as akin to the ergonomic revolution in product design in the 1980s. Auto interiors changed dramatically at that time thanks to ergonomics, with the shape of each button pushed and stretched like dough into gentle pillows of controllability. The tools available now help to justify design decisions in a way that is clear and economically accountable to clients. Where structural engineers have traditionally enjoyed more creative leeway—as well as architectural influence—in design decisions, mechanical engineers have been held to cost factors associated with conventional marketplace equipment. As any mechanical engineer will tell you, they are usually relegated to the m/e/p “back-of-house” spaces architects love to hate. But as each building has a more performative relationship toward its environment and energy consumption, mechanical engineers have moved outside the realm of mere specifiers and become more aligned with their architects.

At Caltrans, Eugene deSouza, a mechanical engineer in Arup’s Los Angeles office, worked with Morphosis in an iterative design collaboration before settling on the custom double-skin curtain-wall system of glass-and-metal mesh. The DOE2 program output helped settle issues such as the width between the two layers, the metal skin’s transmissivity, the coatings on the inner glass layer, and the cavity’s target ambient temperature. DeSouza says the model showed the metal skin reduced heat gain in the building by 25 percent, which was more than enough to justify its cost. “We try to sell energy modeling with all of our projects, but we do it as an add-service,” he says. “It should be an industry standard.”

 

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