Greening of America 1

Noah Maximov

Education 2020

14 November 2009

The Greening of America

Back as far at the days of Babylon, nearly 2700 years ago, people have used green roofs;

the famous Hanging Gardens, one of the Ancient Wonders of the World, is one example. Later,

the people of Northern Scandinavia built green roofs made out of sod, which was then placed on

top of wooden beams and birch bark. However, whereas the Hanging Gardens were created by

King Nebuchadnezzar II for cultivation and aesthetic reasons, Scandinavian sod roofs were built

in order to insulate homes and conserve energy (“The History of Green”). It wasn’t until the

1970’s that technological advances led to the creation of green roofs that are both functional and

pleasant to the eye. Although the United States has been slow to “warm up” to the idea of roof

greening, Europe has been at it for decades. Germany, for example, has led the way, having built

70 million square meters of green roofs in just the past 20 years (Primeau 35). As the technology

becomes more efficient and less expensive, more and more people are noticing the benefits of

going green and turning towards roof greening as a solution to local and global problems,

including environmental concerns such as greenhouse gas emissions, urban air quality, and clean

drinking water. Today, roof greening is viewed by many as an effective way for individuals and

businesses to help the environment and make themselves healthier, all while reducing costs and

increasing profits.

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Economic Benefits

There are many economic benefits to using green roofs on both residential and commercial

buildings. First and foremost, roof greening creates jobs in several different industries. The

initial designs and plans for a building’s green roof help employ local engineering professionals,

landscapers, and contractors. Then, once the layout has been designed and the calculations

made, the necessary roofing materials, including roofing membranes, repellent layers, drainage

layers, curbs and irrigation systems, can be ordered and delivered, which provides work for the

manufacturing and supply industries. One study conducted in Germany estimated that their

roofing industry employs approximately 12,000 people, and they predict that number could go

up to 100,000 if all of Germany’s roofs were greened (“Green Roofs Benefits”). Finally, garden

nurseries, especially those geared for green roofs, gain business through the sale of soil,

fertilizer, plants, and seeds. For example, Amber Kusmenko of New York City, a private

homeowner looking to put a garden on the top of her roof, had to purchase 4,000 pounds of soil

for a small 200 sq foot garden (Shulman). That’s thousands of dollars for just soil; it doesn’t

include the fertilizer, plants, seeds, and other materials needed to nurture a successful garden.

Businessmen aren’t the only ones who profit from green roofing. Green roofs save owners

money because they last longer. Both traditional and green roofs have waterproofing membranes

underneath the surface, protecting them from water damage. However, green roofs are better at

protecting these membranes from UV rays and extreme temperature fluctuations. In fact, some

estimates claim that green roofs can last twice as long as their conventional cousins (“Center for

Architectural Ecology”). Better protection for roof membranes can also have two more cost-

saving effects. City governments will save money because less material waste from fewer

damaged roofs will increase the lifespan of existing landfill sites. In addition, since green

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roofing lasts longer, maintenance repairs won’t be needed as much and owners will save on

replacement parts (“Green Roofs Benefits”; “Center for Architectural Ecology”).

Owners also save money because green roofs are more energy efficient. In summer, green roofs

protect buildings form direct solar heat, while in winter the added insulation minimizes heat loss.

Studies have even shown that shading the exterior of a building is actually more effective than

installing internal insulation (“Center for Architectural Ecology”). When buildings stay cooler in

the summer and warmer in the winter, less energy is spent on air conditioning and heating

systems, so owners can save significant amounts of money. The amount of savings depends on

the size of the building, climate and type of green roof. Numerous studies have been conducted

to verify the effectiveness of green roofing. A group called Environment Canada conducted a

simulation and determined that the average one story building with a grass roof could reduce

summer cooling needs as much as 25% (“Green Roofs Benefits”). In a separate study, Karen Liu

of Canada found that a 6 inch thick green roof reduced increased solar heat by 95% during the

summer, while heat loss in the colder months was reduced by 26%, compared to a traditional

roof (“Green Roofs Benefits”). In the U.S., a study was done to determine the cost-saving

effects of placing green roofs on every roof top in the city. The results indicated that the city of

Chicago could save as much as $100 million per year just on reduced use of air-conditioning

units alone (Primeau 35).

Social Benefits

It might seem obvious to some that there are economic benefits of creating green roofs. What is

probably less obvious are the social benefits. For one, green roofs have been shown to decrease

the ground level ozone by reducing the ‘Urban Heat Island Effect’ (“Green Roofs Benefits”).

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The ‘Urban Heat Island Effect’ happens during the summer, when hard reflective surfaces, like

traditional roofs, reflect the sun’s heat back into the air, increase the temperature within an urban

area, and create smog. By reducing smog and higher temperatures, people, especially the

elderly, can avoid respiratory-related illnesses (like asthma), reduce the severity of those

illnesses, and reduce the need for medication (“Green Roofs Benefits”; “Center for Architectural

Ecology”).

In addition to illness prevention, green roofs exhibit a natural beauty and serenity that provides a

restorative benefit. Studies have shown that relaxing in a natural setting is important for helping

people cope with stress and in meeting other non-stress related needs. A different study found

that a natural setting helped hospital patients heal more quickly. In that study, patients were split

into two groups. One group was given a view of a beautifully landscaped yard, while the other

group was given a brick wall to look at. Results showed that the former group received better

evaluations from nurses, took fewer painkillers, and generally had shorter hospital stays than the

brick-wall-group (“Green Roofs Benefits”).

Greening one’s roof can also bring people and communities together. The cost of building a roof

garden is expensive; estimates range from $10 to $15 per square foot (Primeau 4). In order to

afford a roof garden, schools, organizations, and co-ops have learned to pool their resources

together. One example is Paula Crossfield’s Lower East Side Co-op, in New York City.

Determined to have a roof garden on the top of their building, she persuaded the co-op’s board

members to contribute $3,000 each to build their 400 square ft roof garden. After volunteering

to provide the seeds for the garden, transplant the plants once they were big enough, and do the

harvesting, Paula was eventually able to share the fruits of her labor: zucchini, brussels sprouts,

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squash, and watermelon, just to name a few (Burros D1). Another example of a community

coming together is the Glide Memorial Church, located in San Francisco. One of its members,

Maya Donelson, had studied architecture and environmental design and used those skills to

manage the church’s Graze the Roof Project. The food grown by this 900 sq. ft roof garden is

donated to the volunteers and children in the neighborhood, who in turn spend at least one day

each week working in the garden and learning how to cook what is grown (Burros D1).

Environmental Benefits

Probably the most obvious benefit of making roofs green is the positive effect it will have on the

environment. In addition to halting the ‘Urban Heat Island Effect’ mentioned above, green roofs

can be helpful in halting the Greenhouse Effect. Buildings with green roofs use air conditioners

less because all of the plants, crops, grass and other greenery act as natural insulators and absorb

the heat through the air through a process that is known as evapotranspiration (“Green Roofs”).

Since air conditioners produce a lot of the world’s greenhouse gas emissions, the use of green

roofs translates into a decrease of these emissions. In addition, through scientific processes, the

vegetation on top of green roofs naturally removes dust and pollutants from the air, improving air

quality and further minimizing the Greenhouse Effect (“Green Roofs”).

While one of the benefits of roof greening is cleaner air, another benefit is that green roofs

reduce stormwater runoff. In a really heavy downpour, runoff can overwhelm a city’s

stormwater infrastructure, causing gutters and sewage systems to overflow and damaging natural

waterways and endangering fish habitat. Green roofs can help minimize this damage. First, the

vegetation on top of a green roof naturally retains some rain and later releases it back into the air

through evaporation. This decreases the volume of water that spills onto the streets and reduces

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the chance of overwhelming stormwater infrastructure. Second, the soil on a green roof absorbs

some of the rain, decreasing the speed by which water travels through the sewage system and

further decreasing the chance of an overflow (“Center for Architectural Ecology”). When the

flow of water from a rainstorm is lessened and slowed, it is less likely to pick up oil and other

harmful particles from driveways and roads, less likely to overflow into the sewage system, and

less likely to contaminate the city’s stormwater. Since stormwater naturally runs into local lakes

and streams, cleaner water means less water pollution, which in turn means cleaner drinking

water for us and less damage to the fish habitat and other related ecosystems.

Conclusion

Although some say that roof greening is not viable, more and more homeowners and businesses

are taking a serious look it. It is true that the initial costs can be very high; at $10 per square ft.,

Amy Mundson’s small garden would have cost her about $2000, while Maya Donelson would

have paid $4000 for hers. However, in the long-term, the measureable benefits simply outweigh

the costs. There are also those benefits that can’t be measured, like serenity, piece of mind, and a

personal connection to the environment. What one can measure is the positive influence that

roof greening has on individuals, communities, and the environment as a whole. In this age of

global warming, and at a time when the United States is looking for a way to end its dependence

on fossil fuels and jumpstart its economy, one gets the feeling that roof greening could play an

important role. Perhaps the days of Babylon are upon us again.

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Works Cited

Burros, Marian. “Urban Farming: A Bit Closer to the Sun.” NY Times 16 June 2009: D1. Print.

14 Nov. 2009.

“FAQ’s.” Center for Architectural Ecology. British Columbia Institute of Technology School of

Construction and the Environment. 2006. Web. 14. Nov. 2009.

<http://commons.bcit.ca/greenroof/faq.html>

“Green Roofs.” United States Environmental Protection Agency. 9 Feb. 2009. Web. 23 Nov.

2009.

“Green Roof Benefits.” Green Roofs for Healthy Cities. 12 Aug. 2009. Web. 14 Nov. 2009.

Primeau, Liz. “Green Roofs: They’re a Modern Take on the Old Sod Roof, with Environmental

Benefits.” Canadian Gardening Vol. 14, No. 6 (Sept. 2003): 32-36. Proquest. Web. 14

Nov. 2009.

Rodriguez, Reden. “The History of Green Roof Technology.” ifenergy.com. 27 Sept. 2006. Web.

23 Nov. 2009.

Shulman, Robin. “Raising the Roof.” The Washington Post 12 Sept. 2009. Print. 14 Nov. 2009.