Page 19 - Green Builder Magazine Nov-Dec 2017 Issue

curtail a building’s carbon emissions in the process. Living roofscapes
depend on a series of carefully designed layers that ensure the roof
itself is protected, rainwater is filtered and drained, and plants can
thrive. If aiming for performance with minimal inputs, they may
have shallow soil to support a simple carpet of hearty, self-sufficient have double the life span of conventional ones.
groundcover such as sedum. Often called stonecrops, these flowering People who live, work or play near green roofs enjoy more natural
succulents cover more than 10 acres atop Ford’s truck plant in beauty and greater well-being—the result of biophilia, humanity’s
Dearborn, Mich. innate affinity for the natural world. At the same time, building
Green roofs can also have intensive systems to sustain full-fledged developers, owners and operators enjoy increased property appeal
gardens, parks or farms—places where people can rest, recreate, and value. Green roofs bring what people love to encounter on the
and raise flowers or food. That is how once-unused rooftops across ground to elevated yet often wasted spaces. Land is generally the
Brooklyn have become a mecca of urban agriculture. most limited urban resource, but green roofs can create acres and
acres of opportunity for green space and the climate benefits that
Different Shades of Green come with it.
The intensity of investment, structural requirements, installation and To see the green roof on Chicago’s City Hall or Singapore’s
upkeep depends on the level of greenery chosen. Though upfront Nanyang Technological University is to imagine the breadth of
costs for green roofs are higher than those of their conventional the opportunity atop buildings. These signature projects and other
cousins and some maintenance is required, returns are compelling demonstration efforts—such as those atop bus stops, visible to
and long-term costs are comparable, sometimes lower. The soil pedestrians and passing cars—inspire wider public support. Hot
spots of implementation, such as Germany, offer a key lesson:
and vegetation function as living insulation, moderating building
CREDIT: D. JANDY/FLICKR temperatures year-round—cooler in summer, warmer in winter. Construction incentives for green roofs and building policy that
encourages or mandates their use are twin drivers of proliferation.
Because the energy required for heating and air-conditioning is
curbed, greenhouse gas emissions are lower, as are costs. On the floor
They are the stimulus for scaling—from oddity to ordinary.
To raise the ratio of green in Singapore, for example, the
below a living roof, energy use for cooling can drop by 50 percent.
Green roofs also sequester carbon in their soil and biomass, filter government covers half the cost of green roof installation. Chicago
air pollutants, reduce rainwater runoff, support biodiversity within fast-tracks permits for buildings with green roofs. Regulations around
cityscapes, and address urban heat islands—benefiting not just the storm water control and retention also can encourage adoption of
floors beneath but nearby buildings as well. Because vegetation green roofs. In addition, clear and consistent industry standards
protects the roof itself from the elements and UV rays, green roofs and capable architects, engineers and builders can ensure quality.

CREDIT: RUTH HARTNUP/FLICKR

Another round, please. The City of San Francisco’s green roof mandate is expected to make projects such as this domed development at the
California Academy of Sciences a common site among new residential and commercial construction.

www.greenbuildermedia.com November/December 2017 GREEN BUILDER 17

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