Page 164 - The Green Building Bottom Line The Real Cost of Sustainable Building

LEARNING FROM A LEED PILOT PROJECT 143

finishes are varied. A wide brick walkway that winds along the fronts of the stores is
interspersed with fountains, plantings, and places to sit, recalling downtown Savannah’s
renowned public squares. It’s both a shopping destination and a gathering place.
If you were to view Abercorn Common from the air, you’d see lots of white and
green—white roof membranes, white concrete parking areas, white “sidewalks” made of
crushed seashells on planted islands in the parking lot, extensive tree canopy, and a veg-
etated garden roof (you’ll hear more about that later). All that white and green helps mit-
igate what’s called the heat island effect, a rise in air and surface temperature in an area.

DE-ENERGIZING THE SITE
Heat islands are formed when cities replace natural land cover such as forest, marsh-
land, and pasture with pavement and buildings. These changes contribute to higher
urban temperatures in several ways. Displacing trees and vegetation reduces the cool-
ing effects of shade from tree cover and the cooling effect produced when water evap-
orates from soil and leaves—a process called “evapotranspiration.” Dark roofs on
buildings and dark asphalt paving absorb and hold heat delivered by sunlight rather
than reflect it. Heat from vehicles, industry, and air conditioners can add warmth to
the surrounding air, further exacerbating the heat island effect. In warm climates in the
summertime, heat islands may contribute to global warming by increasing demand for
air conditioning, thus increasing energy use that results in additional power plant

Figure 5.1 Rainwater-fed fountain, Abercorn Common.