How Green Roofs are Changing the Built Environment

I feel very fortunate to live in a second story apartment just two blocks from the Atlantic Ocean. The unfortunate aspect of living here is the view of a deteriorating blacktop flat roof which is between my neighbor’s bathroom and bedroom windows.

If any roof top needed some greenery – it’s mine. Believe me, I’ve tried appealing to my landlord with before and after designs, creating privacy between neighbors and increasing tenant value tenfold by having a scenic space instead of an eyesore.

Besides the obvious benefits of green roofs, I began researching more to help my cause. Here are some of the roof top basics for any of us working towards transforming an ugly, dead blacktop space into a green one. The first thing I learned is the two classifications of green roofs; intensive and extensive.

Intensive is completely man-made that would resemble any ground level planned garden with a variety of vegetation, pathways, and structure. This type is meant for human access, enjoyment, and generally comes with higher maintenance.

Extensive is created more for ecological use with very low maintenance. Much better for non-bearing roof structures since the substrate depth can be very minimal by using natural spawning vegetation you’d find growing between sidewalk cracks or local fields. Human access is minimal since nature handles most of the upkeep. This is perfect for my situation since my landlord doesn’t allow anyone on the roof; I’m assuming for liability reasons.

Whichever type of green roof is used, there are many universal benefits to having either one. Here are just six of the benefits green roofs provide.

Attractiveness

An aesthetically pleasing garden view increases property value. Hotels, such as the Gaylord Opryland and the Parrot Cay, charge more and have higher retention with rooms facing interior gardens. Not to mention, several studies have proven that people who have garden views recover quicker from illness, need less medication, and have overall a better sense of well-being than those without greenery.

Habitats

When we build, we take away natural animal habitats. By returning local vegetation to an otherwise inhospitable space, we return natural habitats to the local wildlife. The Swiss have shown that through adding greenery to roofs, rare and endangered bird species, as well as hundreds of different insects and small invertebrates will again colonize these areas. They’ve discovered that insects are attracted to these elevated green roofs, which in turn attract other local wildlife that feed on these insects.

Pollution

With the urban areas becoming more and more polluted from vehicles, factory emissions, and urban heat effect, adding more vegetation is essential to combat these issues. With space being a problem in these areas, transforming barren roof tops is an effective way for nature to filter air pollution that can be extremely unhealthy to that population.

Rain runoff

I can attest firsthand that when we get sudden and heavy rain, the lower level of our building can flood as much as five inches with one storm. The storm water runoff can flood our streets, pollute our lakes and rivers with ground containment, overload our sewer systems, and generate billion of gallons of wasted water – our most valuable human resource. A two year study in Portland Oregon showed an extensive green roof with a substrate (soil) depth of four inches absorbed an average of 69% of all rainfall with a 100% absorption rate of 100% during warm months. A German research also proved that an extensive green roof with the same four inch soil depth absorbed 90% of summer rain water compared to 75% of winter rain.  Even the King County Government department of water management recommends to “reduce impervious surfaces at home and increase the vegetated land cover of your property.” They state that roofs, driveways, patios, and lawns are considered impervious surfaces.

Energy Costs

The installation of a green roof verses a traditional one has shown to reduce indoor temperatures. A Canadian study in Toronto, discovered a single story building containing a green roof saved 25% more in cooling costs than conventional single story roofs. In areas, such as Florida, the cost savings would be even higher due to the fact that air-conditioning is needed almost year round.

Roof Life

With all these benefits, I can still see someone like my landlord would say, “this is great and all, but nature is going to destroy my building.” Studies have shown that a properly constructed green roof will outlast a conventional one. Over time, the standard roofing materials break down from ultraviolet light and extreme temperature fluctuations while the vegetation covered roof can absorb much of the harmful UV light and keep roof temperatures much cooler and consistent.  A European research team, Peck and Kuhn, found that a green roof investment will double the life span of a conventional roof.

While this clearly shows the big advantages of transforming our old, hot, nasty roof tops into an economical plant and bird paradise, it still may not be enough to convince my landlord. By the research, it is clear that our European friends are far ahead of us on this practice. However, the more we show our neighbors, clients, and city councils the far-reaching benefits to green roofs; the more they’ll start to grow on our side of the pond.

Sherry has been part of the interiorscape industry for over fifteen years, starting at an entry level job at North Florida's largest greenhouse and currently owning two horticulture companies. At UMaine, Sherry majored in English where she worked part-time writing scripts for a local college TV studio.

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