Due: April 15, 2013
1. Rosenberg, Tina. “Green Roofs in Big Cities Bring Relief From Above.” The New York Times, May 23, 2012. Accessed March 18, 2013. http://opinionator.blogs.nytimes.com/2012/05/23/in-urban-jungles-green-roofs-bring-relief-from-above
Summary: This New York Times article talks about three ways green roofs can help solve environmental problems in big cities, urban heat island effect being one of them. Big cities lack green space due to buildings and “dark surfaces” tightly filling them. This lack causes temperatures in the city to be higher than that of its surrounding areas. The article gives New York City as an example of a city facing this environmental challenge with temperatures that are 7 degrees higher than that of its neighboring areas. It then gives an example of City Hall and how the surface temperature dropped from 169 degrees to as low as 91 degrees from replacing its black tar roof with a green roof full of plants and grass. Another argument presented in the article is the study done by Columbia University and City University of New York, where they found that green roof decreases the “rate of heat gained through the roof in summer by 84%” and “rate of heat loss in winter by 34%.”
Rationale: Data presented in this article on positive effects of green roofs in big cities are exactly what I need to support the final argument I will be making in my research paper: that green roofs are an effective way of mitigating the urban heat island effect. Data I’ve mentioned in the paragraph above as presented in this article are all important to show that green roofs are proven to indeed lower temperature in the summer and retain more heat in the winter. Another thing I really like about the article is that it focuses specifically on New York City a couple of times. With this article, I will be able to make the point that even something as small as changing the color of the roof from black to white can bring about major environmental benefits to the city. It’s important for the city to plan and build wisely because the changing climates are real and a lot more threatening than we believe.
2. Rosenzweig, Cynthia, Gaffin, Stuart, and Parshall, Lily. “Green Roofs in the New York Metropolitan Region.” Accessed February 19, 2013. http://www.statisticstutors.com/articles/debrat-green-roofs.pdf.
Summary: This research report has so much information but once again I will focus on the urban island heat effect in cities. It talks about several types of green roof systems with different layers, vegetation as well as membrane that can be modified and built for the particular goal of the builder. It also mentions that the weight of green roofs can vary as well as the type of plants, grass, flowers, and trees to be planted on the roof. It all really depends on what you want as the builder and allows flexibility in terms of cost. Reduction of temperature will, of course, vary depending on the roof surface chosen. By shading, green roofs reduce heat entering the building itself and consequently help reduce energy usage, greenhouse gas emissions and fossil fuel consumption. This research paper also argues that green roofs are more effective in heat reduction in long term than white roofs. Though the cost may be higher, green roofs do not require the “burdensome maintenance” of cleaning that white roofs require since much maintenance of them are done naturally. Also, green roof’s cooling effect does not diminish long-term as white roofs do.
Rationale: Other than exploring how affective green roofs are, included in my proposal is another question I wanted to examine: how practical would it be to plant green roofs citywide taking the cost, long-term maintenance, and safety into consideration? This report will shed some light onto this part of my research. Though at first green roofs may seem expensive to install compared to regular roofs with no environmental benefits, their long-term benefits far outweigh the cost of installation. Projecting into the future, green roofs reduction of heat absorbed indoors will save incredible amounts of energy used on air conditioning in the summer and heating in the winter. In terms of maintenance of green roofs for the purpose of cooling, I would argue that maintaining them might even be a pleasant and enjoyable activity for those who are responsible.
3. Bass, Brad. “Mitigrating the Urban Heat Island with Green Roof Infrastructure” Accessed February 19, 2013. http://www.cleanairpartnership.org/pdf/finalpaper_bass.pdf.
Summary: This paper tests green roof infrastructure in relation to already existing grassland and how it can further reduce the urban heat island in the City of Toronto. Temperatures of the road are above 50 degrees Celsius while those of forest, grassland, and shelter wood are 20 degrees lower to about 30 degrees Celsius. This demonstrates that urban forestry strategy is effective in keeping the city a lot cooler. Grass at ground level when irrigated cooled the lower boundary layer of the city by 1-1.5 degrees Celsius. While that’s already quite significant, experiment further indicated that vegetation on roofs intensified the cooling effect of the existing grass on the ground by as much as 2 degrees Celsius. Areas being cooled also expanded when green roofs were irrigated. Green roof cooling is more effective in high-density areas, commercial and residential areas. Combined with existing green areas of the city, significant cooling was observed with green roofs.
Rationale: What’s presented in the paper is incredibly interesting. Returning to the very cause of rising temperatures in cities is the replacement of natural landscapes with heat absorbing materials in buildings and on roads. By restoring some green on ground level itself cools the city by a notable degree. Green roofs essentially are grassland that has been elevated to one of the warmest parts of the city: roofs. And it does wonders in reducing heat in urban areas as well. I intend to use this study to argue that green roof infrastructure can produce greater heat reducing effects when combined with existing urban forestry on ground level. It is not limited to work independently. Increasing grass and green spaces in general on ground level while expanding green roofs can significantly cool a much larger area than each can on its own. As I am focusing my research on big cities, particularly on New York City, it is also important to note that green roof especially extend and intensify its cooling effect in high-density areas.
4. Rosenzweig, Cynthia, Solecki, William D., and Slosberg, Ronald B. “Mitigrating New York City’s Heat Island with Urban Forestry, Living Roofs, and Light Surfaces.” Accessed February 19, 2013. http://www.fs.fed.us/ccrc/topics/urban-forests/docs/NYSERDA_heat_island.pdf
Summary: Urban heat island mitigation strategies include urban forestry, green roofs and light colored surfaces. Among the three, green roof as an individual strategy has the greatest effect on the reducing the temperature of the city. In New York City, combination of green roofs and planting trees will yield optimal result in heat reduction. New York City was broken down into seven areas: New York City, Mid-Manhattan West, Lower Manhattan East, Fordham Bronx, Maspeth Queens, Crown Heights Brooklyn, and Ocean Parkway Brooklyn. Average cooling by green roofs for each area at 3 PM was 0.5, 1, 0.9, 0.5, 0.6, 0.7, and 0.8 degrees Fahrenheit, respectively. (These numbers assume that all of available area is redeveloped to green roofs) Mid-Manhattan has highest average cooling degree followed by Lower Manhattan East. This is explained by the fact that these areas have the most flat roof space, 33.8% in the first and 26.6% in latter. Installing green roofs across Brooklyn will also be effective in reducing the temperature of the area as a whole.
Rationale: This report is extremely useful for my paper because it clearly observes the different areas of New York City and how effective green roof infrastructure would be in each. Depending on the area available for flat roofs mitigation of the urban heat island effect varies. Understanding the area can help better prepare and make policies in installation of green roofs and ultimately in the development of heat island mitigation.
5. U.S. Department of Buildings, “NYC Green Roof Property Tax Abatement Program.” January 2010. Accessed March 17, 2013. http://www.nyc.gov/html/dob/downloads/pdf/green_roof_tax_abatement_info.pdf
Summary: Summary of this document should be very straightforward since it is just a list of benefits, requirements on tax abatement. NYC Green Roof Property Tax Abatement Program is established to encourage environmentally friendly buildings. Benefits of a one-year Tax Abatement include $4.5 per square foot of green roof and as much as $100,000. There are nine requirements for a green roof to qualify for an abatement including a drainage layer, insulation layer, weatherproof roofing membrane, root barrier layer, insulation layer, growth medium, maintenance plan, and a vegetation layer. This program is the city’s effort to encourage building owners to install green roofs to mitigate the increasing temperature in urban areas.
Rationale:This is a valuable source for my paper because it shows that the government is actively supporting and encouraging more establishment of green roofs by providing financial incentives for building owners to build them. The mitigating effects of green roofs would only be lastingly effective if it happens in large areas of the city, not just some. The nature of this strategy requires as many areas to be covered with vegetation whether it be grass, flowers, or trees. This is the perfect way to advocate that and allow everyone to actively participate in helping solve the serious environmental problems causing discomfort to most but life threatening to some who can be fatally affected by heat.
6. U.S. Department of Design & Construction. “DDC Cool & Green Roofing Manual.” Accessed March 18, 2013. http://www.nyc.gov/html/ddc/downloads/pdf/cool_green_roof_man.pdf
Summary: This reports examines the cost of green roofs across NYC. There is about 11.5% roof area in NYC, which is about 944,300,000 square feet. New York City has a great potential for green roofs to benefit not only the buildings they’re placed on top of but the city as a whole. If half the roofs in New York City were covered in green, we’ll be able to reduce the urban heat island effect by almost as much as 1.5 degrees Fahrenheit. Average cost of extensive green roofs is estimated to about $10 per square feet. Greening half of the city would cost about $4.72 billion since there are about 944 million square feet available roof space. Energy usage will decline by an estimated amount of $98.4 million and a total of $149.4 million will be saved annually if half the city installed green roofs. In desiring low maintenance of green roofs, one should consider plant species, initial spacing, plant propagule, soil medium death and pre-grown trays or mats.
Rationale: No matter how excellent a strategy is, if it’s not obtainable it is fair to say that such a strategy is not an effective one to discuss. Though the cost of replacing half of NYC’s black roofs with green is not to be underestimated, such a goal is reachable and the lasting environmental benefits of it are worth the investment in the long-term. This source also emphasizes the main point I will argue in my final paper that green roof is indeed effective in reducing heat in urban areas. More green, the better and more green equals more cooling. Proper planning of green roof installation can also help keep maintenance of it low and easier.