To achieve certification, new buildings should include features that encourage the use of alternative transportation, including bicycles and electric vehicles. A building also earns LEED credit for flat surfaces such as roofs and parking lots that offer good storm water management and minimize the effect of “heat islands.”
- Water efficiency. LEED offers credit for structures that consume less water through such strategies as minimized irrigation systems, improved rainwater collection, low-flow fixtures and the reuse of “gray water.”
For example, the New England Patriots’ new CMGI Field features a complete gray water reclamation system that eases pressure on the town's water and sewer systems during the stadium’s peak in-season demand at halftime.
- Energy and atmosphere. Countless combinations of sustainable strategies can optimize total building efficiency for such basic components as lighting, heating and cooling. For instance, improved insulation and windows; motion sensor and daylighting controls; and more advanced heating, ventilation and air conditioning (HVAC) systems all contribute to lower energy expenditures.
The MIT Stata Center — a 430,000 square-foot facility being designed by Frank O. Gehry & Associates to house the school’s Computing Information and Intelligence Sciences Department — incorporates an under-floor air distribution system that uses less energy to heat and cool the building and improves indoor air quality.
Middlebury College’s Bicentennial Hall is another example. This 220,000-square-foot science center — encompassing classrooms, lecture halls, animal areas, a greenhouse, observatory and library — features engineering systems that facilitate energy conservation and ease maintenance. The building has energy-efficient site orientation and an energy-efficient building envelope. It also uses absorption refrigeration to enhance campus co-generation performance, high-performance HVAC systems and energy-conserving lighting control.
The Costs and Benefits
Do these sustainable design features add substantially to the overall cost of the building?
In a well-planned building, the U.S. Green Building Council estimates that sustainable-design features can increase total construction costs by 5% but they can also reduce them. And various strategies in a building — some increasing costs and others reducing them — can help balance out overall construction costs.
For example, more energy-efficient systems can allow cooling or heating equipment to be downsized. Pervious paving and other water runoff prevention strategies can reduce the size and cost of more extensive site stormwater management.
In addition, buildings that incorporate energy- and water-saving designs reduce operating costs. Aggressive and well-thought-out designs can reduce consumption by as much as 50% and lower utility costs by 60 cents to $1.20 per square foot.
Beyond direct cost savings, LEED-certified sustainable design provides other benefits, as well. Building valuations are higher. Vacancy rates fall and tenant retention rise because these buildings provide improved amenities, greater comfort and lower operating costs.
Studies show that healthier indoor environments can contribute to greater worker productivity and reduced absenteeism and turnover. And it has also been found that sustainable design can increase retail sales by using natural light in displays and store layouts.
Julie Paquette is an engineer with Vanderweil Engineers and a leader of the firm’s sustainable design initiatives.
2004 National Green Building Conference
NAHB’s 2004 National Green Building Conference: Bringing Home the Green will be held March 14-16, 2004, in Austin. For more information, contact The NAHB University of Housing at 800-368-5242 x8338.
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