Tag: green roofs

“Urban Heat Island Mitigation Can Improve New York City’s Environment” Response

I feel that many people are aware that a significant urban heat island effect exists in New York City but do not necessarily know how serious it is, what causes it, or even what it is called. For example, whenever there are weather reports on the news, the meteorologists always have to give several sets or ranges of temperatures, those in the city and those in the suburbs and the countryside. The article states that “a difference of at least 1.8oF (1oC) already existed at the beginning of the 20th century between the mean temperature in NYC and its surrounding rural areas, and this difference increased over the 20th century” (2). If this pattern continues, we may soon be able to actually boil eggs or water on the sidewalk or on dark roofs, which just absorb tremendous amounts of heat and radiate it back at night.

Although the daytime temperatures may be the same or similar in both areas, here in the five boroughs, we are practically always warmer at night. This may not be such a bad thing in the winter for us, since that means that our crops do not freeze as much and we have a somewhat longer growing season, but in the summer, this can lead to unbearably stifling nights, especially for those without access to air conditioning or ventilation. In fact, the warmest day that we have endured so far in our lives was probably on July 22, 2011, when we hit 104oF (40oC) after a morning low temperature of just 84oF (29oC), the latter of which is actually our average high temperature for the month of July (sorry if this is a bit wordy!). Combined with the humidity and lack of a breeze, that day was truly hellish beyond comparison. Speaking about ventilation, while the urban heat island has definitely contributed to record power usage, it might also be simply caused by an increasing population and thus a larger consumer base, but then again, the two are related to each other.

On the other hand, I should not complain, since there are so many out there who did not have access to air conditioning to cool off at night, humans, animals, and trees alike. The article thankfully mentions many ways that the urban heat island effect can be mitigated. I think cool roofs are good at lowering surface temperatures because of their ability to reflect sunlight due to their materials and light colors, I think that green roofs make better use of a part of a building that is almost always auxiliary and seen as extra space. Their vegetation can be pleasing to the eye, absorb harmful chemicals and pollutants, and even enhance the process of evapotranspiration; just imagine how refreshing it is to be welcomed by cool rain after a hot day, and green roofs can multiply this effect. New York City, and just about any other large metropolis on the planet, will always have an urban heat island effect, but we can at least tame it to the point that we can drastically reduce pollution and temperature fluctuations, and make them more sustainable and livable for many generations to come.

“Green Roofs as a Means of Pollution Abatement” Response

This paper definitely contained a lot more hard science than many of the other ones that we have read, especially when it came to discussing some of the biology and chemistry in the methods of pollutants being removed and the results of the dozens of experiments and studies being performed. There was even a whole section dedicated to explaining the criteria for the selection of articles to be used as references for the paper. Despite this, Rowe clearly demonstrated the many benefits of having green roofs, other than the most apparent one, which would probably be their aesthetic appeal resulting from lush, verdant vegetation covering up once-useless wood and shingles.

Green roofs reduce air, water, and noise pollution, mitigate the effects of the urban heat island, take up less space in landfills, release less carbon dioxide, and provide countless positive outcomes to many aspects of human health, especially physiological and psychological. One particular statistic that I found interesting was that “emissions from coal fired power plants could be reduced by 350 tons of NOx per day in Los Angeles by reducing the need for air conditioning…[this] results in a savings of one million dollars per day” (Rowe 2102). Los Angeles might have a much different climate than New York (mild, wet winters and bone-dry, warm to hot summers) and topography (with all of its valleys and mountains), but its metropolitan area has more than eighteen million people, so this proves that green roofs can be implemented on a large scale in some of the most populous urban conglomerations in the world.

Not surprisingly, green roofs are not foolproof and have a few drawbacks. It was mentioned that “particulate matter cleaned from the air that adhered to leaf surfaces will be washed off by rain and eventually leach into the stormwater system, thus trading air pollution for water pollution” (Rowe 2104). Furthermore, only the magnitude and frequency of precipitation, mostly rain, was discussed; what about snow, sleet, hail, ice, or other meteorological events, such as extremely hot or cold temperatures and wind? Lastly, it seems that green roofs will take a giant amount of time and effort to plan, ranging from engineers and architects discussing the design appropriate for the building to botanists selecting a certain group of species to other workers maintaining the green roof for years to come. Regardless, this idea looks extremely promising, and a cost-benefit analysis will likely allow green roofs to enter the mainstream if they have not done so already.