High Performing Buildings - Fall 2008 - (Page 12)

Don’t overlight hallways. Use automatic dimming or stepped lighting strategies that are tied to the energy management system to ensure peak load reductions. Although not appropriate in all applications, it makes sense for a gymnasium that can be dimmed by 5 or 10 footcandles during the highest peak cooling hours. Using ganged-fluorescent light fixtures in daylit gymnasiums can cost less. Install lighting in banks running parallel to the exterior wall that provides daylighting into the space. Mechanical Systems Analyze seasonal and hourly loads carefully to determine fullload conditions. This may allow for downsizing the chiller without significantly impacting comfort. When selecting cooling equipment, accurately account for the benefits of daylighting in terms of cooling load reduction. Minimize turns and reduce friction when laying out chilled and hot water lines and mechanical ductwork. If the mechanical design provides for more than one space to be on the same zone, consider orientation and use patterns. Optimize the mechanical system as a complete entity to allow for the interaction of various building system components. Don’t oversize the equipment, particularly the cooling. Use displacement/stratification strategies to condition occupied spaces. This benefit often can be used in daylit classrooms that have higher ceiling areas, media centers, multipurpose spaces and gymnasiums. When sizing mechanical equipment, investigate unit sizes. It may make more sense to improve the energy efficiency of other design elements (insulation levels, etc.) to reduce the overall cooling load downward to match the next unit size. The net savings will include both the calculated tonnage difference and the cost associated with the difference between unit sizes. If the next best option is to extend the city sewer line a half-mile or more to the school site, consider an environmentally sound, on-site waste treatment systems that can cost considerably less and help the environment. A rainwater catchment system that provides 90% of the building’s water needs can, in some cases, be supplemented with a low flow well, mostly for potable needs, to provide a less expensive solution than extending a city water line. Avoid greenwAShing As in the 1970s when energy costs started to substantially rise and everything became “energy-efficient,” everything today is becoming “green.” As a result, it is critical for the environmentally concerned designer to engage in a deeper level of analysis. start with basic objectives such as saving energy and water, helping the environment, improving indoor environment quality and using resources efficiently. Judge the solutions based on impact. Considering the budget, determine what strategy or groups of strategies will make the most positive impact. for example, a roof garden is a popular strategy being implemented by architects over another strategy that meets the same objectives with less cost and greater positive impact: a rainwater harvesting system that incorporates a white, single-ply roofing membrane. initially, roof gardens cost anywhere from an additional $9/ft2 to $20/ft2 when the soil depth is 2 in. or 3 in. They cost even more when the depth reaches 6 in. or 8 in. or more. But, the net cost for a white, single-ply roofing membrane and rainwater harvesting system that provides toilet flushing and ball field irrigation for a school is between $2/ft2 and $4/ft2. from an energy perspective, a 2 in. deep roof garden, unlike many earthsheltered buildings that incorporate 2 ft of earth, provides no lag-time benefits and likely increases peak load problems and provides little conductive benefits. Additionally, with shallow soil and darker surface colors, vegetation options are limited, shading benefits become minimal and nonvegetated areas absorb heat. deeper soil improves performance, but it also increases costs. from a storm water standpoint, roof gardens have some benefits in that 2 in. deep soil with 35% water retention can absorb up to 0.7 in. rainfall. unfortunately, roof gardens often are watered and, in some cases, fertilized for a couple of years until vegetation is established. However, the rainwater/white roof strategies can save over 5% on the energy bill, 80% water and retain up to 2 in. of rainfall for a fraction of the cost. despite cost and environmental benefits of the rainwater/white roof strategy, what is implemented most often? roof gardens. 12 HigH Performing Buildings fa l l 2 0 0 8

Table of Contents for the Digital Edition of High Performing Buildings - Fall 2008

High Performing Buildings - Fall 2008
Contents
Lessons Learned
Green on a Budget
ASHRAE Sets Example: ASHRAE Headquarters
The Lavin-Bernick Center for University Life
Spectral Services Consultants Corporate Office
Advertising Index

High Performing Buildings - Fall 2008

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