One of the concerns of the green building movement is how to move toward a zero-carbon footprint for buildings in which people will still want to live, play and work. Current green building rating systems such as LEED focus primarily on reducing impacts from conventional building construction and operations, but do not "guarantee" an environmentally positive outcome. To meet this challenge, leading architects have begun designing "positive impact" buildings that actually produce more energy than they consume, restore habitat and clean the water they use. In 2006, to promote this approach, the Living Building Challenge was launched by the Cascadia Region (Pacific Northwest and British Columbia) Green Building Council.
"At the heart of the Living Building Challenge is the belief that we need to move quickly to a state of balance between the natural and built environments," say the organizers.97 According to this assessment framework, living buildings should exhibit the following performance characteristics:
• Build only on previously developed sites.
• Set aside habitat permanently, acre for acre, for each new development.
• Use net zero energy, subsisting entirely on natural flows of sunlight and wind, measured on an annual basis.
• Treat and reuse all water onsite, using natural rainfall (except for potable water requirements for drinking and washing).
• Generate almost no construction waste.
• Discharge no onsite wastewater or stormwater; treat and recycle all wastewater onsite.
• Use no materials with demonstrated toxicity to humans or the environment, including heavy metals, formaldehyde, PVC, chlorinated fluorocarbons and halogenated flame retardants.
• Use materials and services from nearby, less than 250 miles in the case of stone and aggregate.
• Offset carbon dioxide from construction activities through the purchase of carbon offsets.
• Use only wood products certified by the Forest Stewardship Council.
• Provide operable windows for fresh air and daylight in each occupi-able space.
• Educate the public about living buildings.
• Design buildings that are truly beautiful and that elevate the human spirit.
Differing from the LEED rating system in one essential feature, the Living Building rating system has no points to acquire, only prerequisites. In other words, the Living Building is designed to be "eco-effective" and not merely "eco-efficient." It is a building that is positively good and not just "less bad." This concept presents a major challenge to architects and engineers, because it doesn't allow them to rest on their laurels until they have completely eliminated adverse environmental and social impacts of buildings.
Recent work in China, involving master planning by the internationally renowned firm Arup for a major new Dongtan Eco-City immediately west of Shanghai, shows that for a development to have a zero carbon footprint, working on individual buildings is not enough; attention must also be paid to common energy-using systems and to transportation energy
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