Despite being an Arizona native, I find it difficult to acclimate myself to the desert’s scorching heat. The state reached a record high temperature for August of 117 degrees, and the torment ceases to end at night since the Phoenix-metropolitan area is an urban heat island. However, it interested me to see that there are construction projects within the Valley that are putting forth the effort to battle the AZ heat bluster, and mitigate the sweltering summer weather through the use of green roofs.
The Tempe Transportation Center (TTC) is one of the first buildings of its kind in AZ that is transforming the standard concrete rooftop into a lush garden. The roof is covered in drought-tolerant native plants that can withstand the dry weather, as well as built-in systems to recycle/reuse water. Its rainwater recovery system provides water for the building’s drip system and for the power-washing of public plaza areas. The separate grey-water system recycles shower, sink, and drinking fountain water to refill toilet basins. According to Parsons.com, a firm focused on environmental construction, TTC’s green landscaping and design allows the company to use 52% less energy, reducing the amount of waste heat generated by energy usage.
Other cities like New York City and Chicago are morphing their concrete landscape into stunning, sustainable, green works of architecture. These cities are using their ample supply of rooftop surfaces to reduce greenhouse gases, increase energy efficiency, and capture storm-water run-offs. The vegetated roofs consist of plants that have absorbent leaves, tough roots, and high drought, wind, frost, and heat tolerances – all necessary attributes for sky rise roof deck surfaces. Moreover, some buildings like those that are a part of the NYC CoolRoofs project are painting white reflective coatings on roofs to reduce energy use, cooling costs and carbon emissions. According to the Economist.com in its latest article “Greening the concrete jungle,” a green roof can cool rooftop temperatures as much as 50 degrees Fahrenheit compared to typical temperatures radiated by tar roofs due to the additional layer of insulation provided by the added soil and vegetation. The article reports the air temperatures above Chicago’s City Hall being 10-15 degrees Fahrenheit lower than those above the adjacent black-tar roof of the Cook County Building, therefore reducing the amount of energy needed to cool the building during the summer.
Greening roofs seem to be the perfect solution for greenhouse gas mitigation because of their potential to reduce energy usage; however I was shocked to discover the trendy roofs have caused a lot of controversy for cities. Some cities, like Toronto are trying to force green roofs through city bi-laws, making several powerful land development industries outraged due to the additional costs associated with building green roofs, which will result in a burden passed down to tax-paying consumers of the real estate. According to greenbuildinglawblog.com, non-unionized workers have been filing claims with the National Labor Relations Board alleging developers are unjustly overcoming associated green roof costs by paying workers as landscapers, not roofers, meaning these workers receive $20 less per hour than typical roofers. In “Green roofs are the way to go” by Gilman Ouellette, opponents argue that there is insufficient data collected for a comprehensive life cycle assessment of green roofs to assume they can effectively alleviate the urban heat island effect on a city-wide scale.
Do you think cities are overstepping their bounds by trying to strong-arm environmental regulatory tactics? Are green roofs just the latest green trend with insufficient data to back-up associated benefits? Or should our government offer incentives and tax breaks for green roof construction?
