National Geographic : 2015 Nov
Solar panels Energy-efficient lighting Occupancy sensors Heat- trapping film Watercooled HVAC system Capturing water for reuse 1 2 3 4 1234 ART: ROMUALDO FAURA SUSTAINABLE WATER MANAGEMENT Despite its reputation as a water guzzler, Los Angeles is pioneering ways to capture every drop that falls from the sky. On a floodprone block of Elmer Avenue in the east San Fernando Valley, storm water used to be funneled into drains and out to the ocean. A $2.7 million project has transformed the block into a sponge, capable of collecting enough water yearly to supply 30 families. Rain barrels collect rainwater from the roof and save it for irrigation. Rain gardens replace lawns—and soak up excess water if the rain barrels overflow. Driveways and sidewalks made out of permeable materials allow water to seep through them. By the time storm water filters down to the aquifer below, it has been cleansed of pollutants. Most Hong Kong residents live near mass transit: 43 percent within 1,640 feet, 75 percent within twothirds of a mile. GREEN BUILDINGS Buildings are responsible for approximately onethird of all greenhouse gas emissions, a figure likely to shrink as more cities require municipal buildings to be energy efficient. Increasingly, government office buildings will have solar panels and even gardens on roofs, sensors to douse lights in empty rooms, windows lined with heattrapping film, and energyefficient HVAC systems. The Norwegian city of Drammen is heated almost entirely by water from the local fjord. In 2014 U.S. mayors rated energy efficient lighting as the most prom ising technology for reducing urban energy use and carbon emissions.