Introduction - Living Roofs in Integrated Urban Water Systems - page 8

living roofs alone are unlikely to suficiently regulate city-wide temperature, a
large accumulation of living roofs in city centers could have a positive effect on
the heat island effect (Umweltbundesamt 2012).
1.2.3 A social space for interaction and learning
In addition to its numerous measurable beneits, rooftops create opportunities
for social, cultural and economic value. They can become the social spaces that
form the backbone of cities; places that allow people to deine themselves
through their interactions with their fellow citizens (Watson 2006). All cities have
vast amounts of underused roof space. Roof space is not “left over” space.
Rather, as a building's ifth façade, it is a productive space, one that can help
replenish the social space deicit generated by dense urban development. It is
also an educational space - a place of learning about the natural processes of
the water cycle, food production and wildlife (Ashbury.ca 2013).
Some living roofs are appropriate spaces for urban agriculture as well as a
nurturing place for biodiversity protection. For example, following alarming
reports of worldwide Colony Collapse Disorder, rooftops, including living roofs,
are becoming popular venues for apiculture as a means to offset their disappear-
ance. Honeybees pollinate roughly 30 percent of our entire food stock (Douglas
2010; Dupont 2007; Oldroyd 2007; Spivak 2013; Williams 2008). Other beneits
in urban bee-keeping include educational value, and contributions to local food
economies and cultures, including the hundred-mile diet (Matteson and Langel-
loto 2009; Poppick 2013; Satow 2013).
As a living roof, the ifth façade can enhance viewshed value, particularly
where ground-level green space is limited or beyond accessible or meaningful
view. A viewshed is considered to be the full extent of the area from which the
living roof is visible. For example, adjacent buildings that look over a living roof
are contained within the viewshed, without being owners or occupiers of the
building upon which the living roof is installed. Publicly accessible viewsheds are
considered particularly important with respect to maintaining aesthetics, to
ensure ongoing support for a living roof project. As an architectural surface,
living roofs allow freedom in design ranging from “wild” habitat to a rigid archi-
tectural scheme. Depending on its location in the city and the context of the city
to the surrounding landscape, the living roof's manifestation should consider eco-
logical, environmental, architectural and social points of view.
1.3 ClassifiCations
Living roofs are commonly divided into two basic types derived directly from a
German classiication: extensive or intensive living roof.
An extensive living roof is deined in this topic as:
A single or multilayered living roof system (drainage, growing media, and plants)
designed individually or as composite, manufactured system. The growing media