‘Happiness buildings’ with a green topping

Klinkenborg (2009) says that green roofs are gathering momentum, revealing the driving factors behind – our changing idea of the city, incentives and regulations, improved technology and increased research – and the benefits – moderation of indoor temperatures and street flooding and creation of habitats. He, however, cautions that there are challenges to be met, both technical and philosophical, but says it’s worth the efforts because green roofs, besides being environmentally friendly, can help make people happy.

(The following write-up by Asitha Jayawardena is entirely based on Klinkenborg (2009). For enhanced readability, the reference (i.e. Klinkenborg, 2009) is usually mentioned at the beginning of a section only.)

The rise of the green roofs

A man-made desert. That’s what the urban roofscape is. But there are exceptions, such as the priorie that thrives on top of the nine-storey Vancouver Public Library Building. And such green exceptions are on the rise.

The green (or living) roof is not a new idea. However, it is now increasingly capturing the attention of planning and building professionals around the world – not for its beauty but for its ability to play down the adverse environmental effects associated with the conventional roof.

Klinkenborg (2009) discusses in length what drive green roofs, the benefits they offer, and finally the challenges they pose.

Factors driving green roofs

According to Klinkenborg (2009), the green-roof drive is powered by several factors.

Firstly, our idea of the city is changing. It is no longer wise or practical or even ethical to perceive the city as the antithesis of nature. Therefore, we are finding ways, such as the green roof, to naturalise cities so that they are more liveable for both humans and non-humans.

Secondly, incentives and regulations nurture the ‘growth’ of green roofs. For example, in Portland, Oregon, green roofs are entitled to various incentives, including fee reductions. And in countries such as Germany, Switzerland and Austria, law requires green roofs on the roofs of suitable pitch.

Thirdly, improved technology helps the spreading of green roofs. For instance, thanks to water proof membranes, it is now easier to design green roof systems that capture water for irrigation, allow drainage, support the growth medium, and resist the invasion of roots.

Finally, increasing research is also helping green roofs to spread. Studying their practical benefits, many researchers are focusing on quantifying the performance of green roofs, from storm water runoff to energy efficiency.

Benefits green roofs offer

As Klinkenborg (2009) reveals, green roofs offer financial as well as environmental benefits.

Green roofs moderate indoor temperature of buildings. For example, during the summer in the US, the daytime temperature of a conventional asphalt rooftop can rise as high as 150^oF (i.e. 65^oC), contributing to the overall heat-island effect (i.e. the tendency of the cities to be hotter than the surrounding regions). However, the soil mixture and the vegetation of a green roof act as an insulation, lowering indoor temperature fluctuations of the living spaces beneath, and consequently slashing the heating and cooling costs by as much as 20 percent.

Green roofs moderate street flooding, too. Rainwater falling on a conventional roof runs into storm drains – unabsorbed, unfiltered and nearly undeterred. However, a green roof absorbs rainwater falling onto it, filters it, slows it down and even stores some of it for future use. Thus green roofs in a city lower the likelihood of sewer overflows, extend the life of its drainage system, and return cleaner water to the surrounding watershed.

In cities green roofs provide the badly-needed habitats for a variety of species, such as ants, beetles and crows. Recapturing the negative space within a city, green roofs can together form a chain of rooftop (green) islands that connect the city with the surrounding countryside.

Challenges to be met

Klinkenborg (2009) highlights the challenges that remain to be met – technical as well as philosophical.

Firstly, on technical challenges. According to the proponents of green roofs, most of the technical challenges related to green roofs have been already met. However, the average cost of installing a green roof can be twice or thrice the corresponding cost of a conventional roof. Of course, the green roof is cheaper in the long run due to its energy savings. Moreover, its vegetation shields the roof structure from ultraviolet radiation, extending its life. Therefore, in the long run, the green roof is the more economical option but, to make it more attractive, its initial cost should go down.

Secondly, let’s turn to the philosophical challenges, which revolve around the very idea of what a roof should be and how it should perform. Clients want roofs that are uniformly-green throughout the year and builders and architects prefer interchangeable, standardised, universal solutions. But what is really a green roof?

A green roof is not just a biological alternative to a dead roof; it can be much more than that. It is true that even a standardised green roof is environmentally more desirable than a conventional roof but a green roof can be made even more environmentally beneficial. For some researchers, the goal is to develop green roofs that are both ecologically and socially sound; that is, low in environmental costs and available to as many people as possible.

For Swiss scientist Stephan Brenneisen, a strong advocate for the biodiversity potential of green roofs, what matters is finding easy cheap solutions using locally available materials, relying less on energy intensive materials (e.g. plastics) between the roof structure and vegetation. Thus it is important to make green roofs work in the most sustainable way, using the least amount of energy while creating the greatest benefit for the human and non-human habitat.

Human happiness as a by-product

According to Brenneisen, people feel happier in a building where they have given something back to nature. Millions of acres of dead rooftops are idling in cities around the world, contributing to a variety of environmental problems such as the urban heat island effect. How about returning some of that human footprint back to nature? Such a move will not only be environmentally sound but also generate human happiness as a by-product, concludes Klinkenborg (2009).

Reference

KLINKENBORG, V. (2009) Up on the roof. National Geographic, May, pp.84-103.

The Centre for Alternative Technology http://www.cat.org.uk/

Founded in 1973 in Machynlleth in Mid Wales, the Centre for Alternative Technology (CAT) explores and demonstrates globally sustainable, whole and ecologically sound technologies and ways of life, showing that sustainable living is easy and can also improve the quality of life. Among its key areas are renewable energy, environmental building, energy efficiency, diet and health, organic growing and alternative sewage systems. Its visitor centre attracts 65,000 a year. The other ways it promotes its ideas include a media department and an information service, residential courses (including an MSc), books publication, an eco-shop and a mail order service, and volunteering.