The document discusses the history and benefits of green roofs. It describes how green roofs were used as far back as ancient Babylon but became more advanced in the 1970s. While Europe has embraced green roofs, the US is just starting to adopt the practice. The document outlines economic, social, and environmental benefits of green roofs, such as job creation, energy savings, improved air quality, stormwater management, and increased wildlife habitat. It concludes that while initial costs are high, green roofs provide measurable long-term benefits to building owners, communities, and the environment.

1. 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.