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Tuesday, January 01, 2008
Thermal Energy Storage: An Excerpt from Jerry Yudelson’s “Green Building A to Z”
Thermal energy storage is a simple concept: make ice or chilled water when power is cheap, then avoid buying electricity to operate mechanical cooling systems when it is expensive. Just about any large office building, hospital, hotel and similar 24/7 facilities can benefit from thermal energy storage. As utilities are forced to increase peak-period electrical rates to short period of time.
avoid brownouts and blackouts on summer afternoons by limiting demand, thermal energy storage systems are beginning to come into their own. They reduce the pressure on the electrical grid and can save building owners considerable money. They also can save money up front, even after paying for their cost, by limiting the size of the HVAC system purchased. They should be thought of as a component of an integrated design project, where the initial focus is on reducing the need for summer air conditioning through overhangs and shading devices, better glazing and passive solar design approaches, not as an end in themselves.
Consider the example shown in the table on page 169. By applying thermal energy storage, the building’s electrical demand is lowered by 400 kilowatt, about a 25% reduction in peak demand. If the utility charges $10 per kilowatt, not an unusual amount, the monthly savings from demand avoidance alone could be $4,000, or nearly $50,000 per year! These savings can continue for many months beyond the peak summer cooling period, because utilities often charge for the instantaneous peak power use in a quarter, or sometimes in an entire year. If time-of-day rates are available from the local electric utility, making power cheaper to buy during off peak hours, the energy cost to produce the cooling would also be lower, further increasing the cost savings from installing the system (only about 10% of ice storage systems provide the full cooling load). In themselves, electric utility “demand avoidance” charges provide complete economic justification for partial storage systems. Time-of-day rates are not needed, but a faster return on investment will occur with them.
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Saturday, December 15, 2007
Salvage Materials: An Excerpt from Jerry Yudelson’s “Green Building A to Z”
“A penny saved is a penny earned,” wrote Ben Franklin. We care about reusing building materials because of the energy and resources they represent. It takes energy to down-cycle them into recycled-content materials (think of old concrete from a building ground into three-quarter-inch aggregate for use in concrete or as the base material for a parking lot or roadway), so why not use them in their original form instead of throwing them away or using them in some devalued form?
LEED recognizes the value of salvaged or reclaimed materials, such as decorative brick, heavy timbers and other framing lumber, doors, millwork, furniture and partitions, by rewarding projects that use them for at least 5% of the total value of all building materials (not counting equipment). On a typical $10 million (construction cost) project, this would represent $225,000 worth of such materials, not an insignificant amount. One benefit of this practice is the development of local enterprises based on deconstructing buildings and salvaging such materials. If you consider how much useful material is saved from old cars by auto salvage yards in every town, you’ll see the benefit of this practice.
With the advent of Web-based auction sites such as eBay and retail/ wholesale reclaimed building materials stores in most large metropolitan areas, there is now a nationwide market in reclaimed building materials for building projects. So, there is no longer an excuse for not being able to find materials. The only issue is their quality and availability, along with transportation and storage costs.
Some creativity might be required to find and reclaim salvaged materials. The first LEED Platinum project, the Chesapeake Bay Foundation building in Annapolis, Maryland, used large wooden tanks from a former pickle manufacturing facility to harvest rainwater from the roof of their new building. The three tall pickle barrels create a strong visual and architectural element at the building entrance.
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Saturday, December 08, 2007
Commercial Market Size
But what about cost? If green buildings cost more and certification costs are
onerous,we would expect that most of the activity in green buildings would
be found in government agencies, schools, and universities: institutions
that can afford to take the long view and invest more money up front to
save money on operating costs year after year. That was certainly the case
early in the development and use of the LEED system,when only about onethird
of the project owners (by area, or value) were private corporations.
Lately, however, the pendulum is swinging: private companies and private
developers now represent the majority of LEED projects (ranked by building
area, or value) applying for registration in 2006 and 2007…
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Saturday, December 01, 2007
Restoration of Sites: An Excerpt from Jerry Yudelson’s “Green Building A to Z”
A goal of many green building projects is to leave the land a better place than it was before. Achieving this goal requires site restoration activities, such as rehabilitating natural drainage systems, replacing wide swaths of green lawns with plants that provide wildlife habitat and replanting ornamental plants with native and adapted species that need far less water and intensive maintenance. As we complete the switch from a predominantly manufacturing economy to one based primarily on services, developers are finding attractive options in paved-over older parts of cities that once supported manufacturing, warehouses and similar industrial uses. Many of these sites were polluted with petroleum products, heavy metals, PCBs and other toxic substances that require remediation before reuse. Even paved-over but unpolluted sites can be converted to offices, retail, hospitality and housing, with considerably more wildlife habitat.
Often the task of the architect and builder is to find a way to place buildings so they don’t disturb what’s already working on a site. Several years ago, I visited the National Conservation Training Center of the US Fish and Wildlife Service in Shepardstown, West Virginia. Located on an upper tributary of the Potomac River, this site is very hilly, like most of the state. The project designers placed 17 buildings on the site, only on the hilltops, leaving the hollows alone. Because of a number of changes of site elevation, the design required many wooden bridges between buildings, sometimes with entrances on upper floors. However, this approach allowed the project to avoid extensive grading and degradation of wildlife habitat, while promoting the very values inherent in the Center’s mission. This is a good example of a smart and wise approach to site planning.
Another interesting project is Tanner Springs Park in Portland, Oregon. Completed in 2005, this park sits on top of about 40 feet of historic fill of the original Tanner Creek. To honor its origins and to provide city residents with a natural park, the landscape architects designed a reconstructed wetlands with a boardwalk over it. This park is now habitat for many creatures including various waterfowl. It is mainly used for passive recreation and helps incorporate sustainability into the fabric of the city.
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