other man-made materials, with a horrific lack of wildlife for as far as the eye can see.
One burgeoning trend in building planning and renovating is trying to change that. The
trend is that of “green” or “living” roofs. Basically a green roof is where vegetation is
planted on building rooftops and allowed to grow.
Green roofs aren’t a new idea; they have been around for hundreds of years. Sod
roofs, as well as roofs made from other living and growing vegetation, were quite
common in Norway (and other parts of Europe) in the 18th century.
Company’s Rogue River Plant. Over 42,000 square meters are covered in sedum and
thing, but is it worth the effort?” The answer is that numerous studies have shown very
interesting and important benefits of living roofs.
The Pros:All over the world corporations, cities, and nations have begun dealing in what is
termed the “carbon economy.” This involves many global entities trying to lower, and
cap, carbon emissions. Within the new carbon economy, these entities buy and sell their
shares of “carbon” to show how Eco-conscious they are and to make an effort to lower
and control carbon emissions. This economy also involves taking preventative measures
that do lower carbon emissions, or that can at least help to combat carbon emissions in
different ways. Living roofs are one such way to combat carbon emissions.
Living roofs help to mitigate the negative effects of buildings’ carbon footprint by
recreating green space at the roof level. Healthy, growing vegetation on rooftops can
help store and retain CO2 and other pollutants in urban environments. Simply storing
carbon is an asset to an urban environment, but living roofs provide even more ecosystem
services. Along with filtering air and pollutants, green roofs are fantastic for storm water
management. The roofs are designed to filter and sometimes retain storm water. When the
water is released the runoff is far cleaner than if it had come off a regular city roof.
Effect. Studies have shown that most common materials in cities (metals, concrete,
cement, asphalt, ect.) absorb UV radiation and heat during the day and make cities up
to 4ºC hotter than surrounding areas. Even after the sun has gone down these urban
materials continue to radiate heat, so cities do not cool down at night as much as they
naturally should. Large scale studies in Chicago and Washington D.C. have shown that
the microclimates of green rooftops are as much as 4.4ºC cooler than traditionally roofed buildings. Researchers even went as far as to estimate that if all roofs in a major city
were greened, urban temperatures could be reduced by as much as 7ºC. That is a large
difference in temperature, and not only can it have a significant effect on human comfort
and well-being, but it can drastically affect wildlife within cities and near city limits.
Changing temperatures is not the only affect living roofs have on wildlife. In cities
throughout the world green roofs have become vital stopovers for migrating and local
birds. Living roofs can provide important feeding and nesting habitats for endangered and
displaced birds and other wildlife. Providing habitats for animals within the city helps to
raise biodiversity within a usually sparse, human-made and human-dominated landscape.
economical. They should be implemented by more architects and city planners in the
Public commentary focusing more on green roofs can be found here.
Gill, S.E., J.F. Handley, A.R. Ennos and S. Pauleit. “Adapting Cities for climate Change: The Role of the Green Infrastructure.” Built Environment Vol 33 No. 1, page 122-123.
Grant, G., Engleback, L., and Nicholson, B., Green Roofs: their existing status and potential for conserving biodiversity in urban areas [Report No. 498], Publisher: English Nature Reports (2003)