Reducing Urban Heat Island Effects While Providing Affordable Housing in Bunker Hill

The Bunker Hill Public Housing development is a historic public housing building, home to a large population of racial and ethnic minorities, that requires major redevelopment and repair to enhance the safety of its residents. The Boston Planning and Development Agency (BPDA) recently approved a $1.46 billion redevelopment for the property, a part of which is allocated to remove and replace ~250 mature trees around the public housing units. Removal of these trees would affect an already vulnerable population significantly more exposed to the effects of heat events, including heat-related stress, morbidity, and mortality, which will worsen with climate change in the coming years. While the BPDA proposal seeks to address the issue that the area already experiences 20% less cooling due to a lack of vegetation by replanting more trees, their estimated timescale of more than a decade for the canopy to just return to its current size is concerning. In order to mitigate the added heat stress caused by the tree removal, we propose the supplementary action of installing green roofs on buildings throughout the development. These green roofs would continue to provide cooling and beneficial community services even once the tree canopy has returned. These measures will serve as an appropriate stopgap measure until the canopy can return to size and expand as well as providing the community with the same co-benefits, such as air quality improvement, noise pollution reduction, community spaces, and locally grown food from community gardens, that more affluent parts of the city already experience. The installation of green roofs and supplemental vegetation will take only 0.25% of the entire redevelopment project budget and will have a large return in community wellness.