Green grow the buildings: from high-tech to low-tech, sustainable technologies are blossoming
The term "green building" hasn't reached Webster's dictionary, but it's certainly in the news. The University of North Carolina recently unveiled a sustainably built addition to its school of nursing. Johnson County, Missouri, hopes to complete its first green building, a county office building, by January. Financial services company KeyCorp has just received Leadership in Energy and Environmental Design certification from the U.S. Green Building Council for its 750,000 squarefoot campus in Brooklyn, Ohio. And in April, Gov. Christine Gregoire made Washington the first state to require that all schools and other public buildings be built green, using the LEED standards. (So far, the U.S. Green Building Council is the only national organization that rates green buildings, after an extensive application process, designating them as certified, silver, gold, or platinum.) Hundreds of other municipalities, nonprofits, corporations, homeowners, architects, and developers have also chosen to go green, using standards from LEED, the National Institute of Building Science's Whole Building Design Guidelines, and local green building programs. What is green building? In a nutshell, it is designing and constructing buildings in a way that minimizes their negative impacts on the environment. More specifically, it concerns a building's efficient use of energy, resources, and water; sustainable site planning; and indoor environmental quality. No single technology can make a building green. Since a building is not merely the sum of its parts, but a collection of interdependent components and systems, building green requires a holistic, systems-based approach. Understanding how certain systems affect others is essential to successful sustainable design and construction. For example, a tighter building envelope allows for the installation of a smaller HVAC system, but also diminishes the building's capacity to expel excess moisture. Still, there are some exciting technologies that help make green building easier, cheaper, better looking, and, well, greener. Further, innovation will only increase as green building moves into the mainstream. Here are just a few innovations that experts say we should be keeping an eye on. Saving energy Energy efficiency is what springs to mind when most people think of green buildings, especially if they happen to be paying their heating bill or filling their gas tank at the time. Considering the U.S. Department of Energy's finding that commercial and residential buildings together represent more than a third of primary energy use and more than two-thirds of electricity consumption, energy efficiency is a big deal. Mike Hatten, principal engineer with Solar Architecture and Engineering in Eugene, Oregon, says that two factors contribute to energy efficiency in buildings: load-reducing technology and the systems that supply a building's energy needs. Those systems, particularly HVAC equipment, are becoming more efficient. Variable speed motors in fans and pumps, for instance, allow equipment to run only when needed, rather than constantly or on a fixed schedule, making it more efficient and reducing cycling, which shortens the life of the equipment. The American Society of Heating, Refrigeration and Air-Conditioning Engineers, which creates industry standards and guidelines, last year released GreenGuide, a primer on nonstandard methods and technologies for HVAC practitioners. Those technologies are changing so fast that ASHRAE started on a second edition only months after releasing the guide in early 2004. Hatten says that centralized controls make heating and cooling systems more efficient. "What's really exciting is integrated paths that can control a whole host of components", he says. "Unfortunately, they're about 15 years behind other networking technologies", he adds. "Right now, they don't talk to each other. The HVAC, the fire alarm, lighting, security all operate independently". The most important load-reducing devices in commercial buildings are high-performance, energy-efficient glazing systems, Hatten notes. "Low-emissivity, or "low-e", coatings and spectrally selective coatings help to reduce radiant heat transfer through windows, keeping heat out in the summer and keeping warm air inside in the winter". There is constant, ongoing innovation,” in insulated glass options, glazing, and even glass with integrated photovoltaic mechanisms, says Hatten. “You practically need to check in every couple of weeks.” Several promising possibilities involve the use of chromogenic technology, in which film on the glass alters the level of energy transmission in response to light (photochromic), temperature (thermochromic), or electrical stimulus (electrochromic). The Lawrence Berkeley National Laboratory, which is managed by the University of California at Berkeley, considers electrochromic technology the most promising of the three because it allows users to manually control the level of transparency at the flip of a switch. For systems to work efficiently, building orientation must be taken into account, says Alex Wilson, president of BuildingGreen and executive editor of Environmental Building News, based in Brattleboro, Vermont. He warns that specifying improper glazing can be disastrous. South-facing windows— which allow more light and heat transmission in the summer because the sun is hotter and higher—should be minimized or mitigated. In the shade Roof overhangs, awnings, and other techniques have been used for centuries to block the sun, but they are rarely seen on modern commercial and residential buildings. That is changing. At Portland State University’s newest dormitory, Epler Hall, architects at the Seattlebased firm, Mithun, thought of each building section as a box, and each got a different shading treatment. “Each box responds to its own particular microclimate,” says principal Ron van der Veen. For that reason, large, loftlike indows grace the building’s north facade, while the west features both vertical and horizontal shades. In renovating the Bethel Commercial Center in Chicago, architect and planner Doug Farr of Farr Associates relied heavily on shading. He also took it one step further: His design includes a cornice that provides shading, but also has electricity-producing photovoltaic cells on top. According to Farr, it also defines the “outdoor room” in front of the building, protects the lintels by keeping water off the facade, and shelters pedestrians from the rain. Small holes and spaces in and between the PV panels allow dappled sunlight to fall on the sidewalk, he adds. Solar-generated electricity also comes into play at the Chicago Center for Green Technology, the headquarters of a city program to promote sustainability. There, PV panels mounted on south-facing awnings, an array of roof-mounted panels, and a solar-paneled berm behind the building provide 20 percent of the building’s electricity, says program coordinator Elise Zelechowski. While Zelechowski did not specify what the systems cost (the city spent $5.4 million on construction and renovation of the building, which was formerly a debris crushing facility), she says that Chicago Green Tech expects to see a payback within 10 to 12 years. “We’ll make back our money and then some,” she says. “We’ll be a power producer, giving electricity back to the grid. That’s a powerful place to be.” Running hot and cold Twenty-eight 200-foot-deep wells were drilled on the grounds of Chicago’s green tech center for its geothermal heat pump system. At that depth, the earth’s temperature remains constant at 50 to 55 degrees. Conditioned air (either heated or cooled, depending on the season) flows through pipes to an auxiliary boiler and air exchanger. The facility rarely uses air conditioning. Elsewhere in Chicago, the Center for Neighborhood Technology, a sustainability think tank, uses an innovative thermal storage system to supplement a standard cooling system. Its system consists of a buried tank filled with a glycol solution and small, dimpled plastic balls full of water. CNT pulls energy off the grid at night to freeze the water balls. The ice cools the glycol, which then helps to cool the building. “Basically, we’re saving up cold air at night, when the prices are lower,” says CNT research analyst Lisa McNally. The center participates in the Energy-Smart Pricing Plan, offered by the Community Energy Cooperative and the local electric company, Commonwealth Edison. The program charges customers market price for energy, which varies depending on demand. Energy is more expensive at noon on a summer day, for example, than it is 10 hours later, when less cooling is needed. A goal of the program, which is also available to residential customers,is to encourage users to examine and alter their energy consumption patterns. To be energy-efficient, a building must be well insulated. Each of the 280-square-foot studio dorm rooms at Portland State’s Epler Hall has its own mechanical heating system, but many students don’t turn the heat on. Efficient framing and insulation—fiberglass batt with an R-value of 21—means they don’t have to, says Ron van der Veen. They stay toasty from the heat expended by their TVs and computers. Exhaust heat at Epler is run through a heat exchanger to preheat air for the building’s corridors. In the summer months, the building is cooled using natural ventilation. Although numerous insulation options exist, Alex Wilson says there are no dramatic innovations. “The innovation is in building science—understanding the flow of moisture through buildings,” he says. Wilson and others—particularly Joseph Lstiburek, of the consulting firm Building Science Corporation— point to excess moisture in buildings as a serious concern. It causes mold and mildew to grow, and that can affect structural integrity and indoor air quality. Lighten up Lighting may not be something we think about often. You flip a switch and it’s there. But the experts say that lighting heavily impacts energy efficiency, thermal comfort, and even productivity. “Often, lighting should be the number one green design issue in commercial buildings,” says Wilson. The most ideal source of lighting is free and widely available: the sun. But the usual office set-up relies on banks of fluorescent lights that illuminate every square inch of the interior. Further, the typical office’s interior design consists of an outer ring of Ron Still http://p2pays.org/
