Fifty Shades of Green
https://www.nytimes.com/2019/10/09/realestate/the-green-roof-revolution.html
As I highlighted in my very first post a month ago, urban vertical farming and the idea of urban greenery are not new ideas. A variation of extending greenery into the urban landscape is the construction of rooftop gardens, also known as green roofs.
This is more than just about aesthetics. Green roofs meet the urban greenery requirements legislated into law by cities in the developed world, such as Toronto, Singapore, and New York City. At the same time, they reduce greenhouse gas emissions by reducing ambient temperatures and indirectly, the cost of cooling buildings. More interestingly, they reintroduce the absorptive capacity of natural vegetation lost to concrete when buildings replaced nature. In other words, in the event of torrential downpours, which will become increasingly common with climate change in some parts of the world, the amount of surface runoff rapidly channeled into sewers and drains is reduced, thereby decreasing the propensity of urban flash flooding and sewer overflows as is common in certain cities in the United States, such as Kansas City, MO, and Jersey City, NJ.
Research laboratories such as The University of Toronto’s Green Roof Innovation Testing Laboratory and companies such as Columbia Green Technologies have revolutionized green roofs by adding sensors. They provide data to create a set of metrics upon which green roofs can be benchmarked, measured, and evaluated. Specific combinations of plants and roof designs can be trialed out, tested, and measured before being deployed. This raises the efficacy of each roof in meeting building-centered or city-centered requirements.
The upfront cost of a green roof is one of the major hurdles in increasing its adoption. Cities can thus provide tax breaks for buildings that adopt it while mandating its rollout through legislation. Germany, which has done so since the 1980s features more than 925, 000, 000 square feet of green roofs; Toronto, which passed a green roof law in 2009, now has more than 640 green roofs and more than 5, 000, 000 square feet of green roof space to date. Publicly available satellite images from the LANDSAT 8 can calculate the normalized difference vegetation index of urban spaces, thus enforcing these regulations while quantifying their impacts.
