How cities manage the sunlight and rain that falls on them has a huge impact on inhabitants’ health and quality of life. But city leaders and planners generally do not manage or even think about their city’s rain and sun in a systematic way and, as a result, mismanage or undermanage these two great natural gifts. This mismanagement costs cities billions of dollars in unnecessary health, energy-, and stormwater-related costs, degrades city comfort, livability and resilience, and contributes to climate change. These costs take the heaviest toll in low income areas, which are characterized by less greenery and greater unwanted summer absorption of sunlight, resulting in increased temperatures, worsened air pollution, and increased health costs.
This report provides an in-depth analysis of the costs and benefits of cool and green roofs, solar PV, cool and porous pavements, bioretention and expanded tree cover and combinations of these solutions at scale across Washington, DC (the District). The District could reap net benefits of at least 5 billion dollars over 40 years by widely adopting cool roofs, green roofs, solar PV, bioretention, rainwater harvesting, reflective pavements, permeable pavements, and urban trees. Benefits valued include energy cost savings, improved air quality and public health, reduced stormwater runoff, climate change mitigation, and increased resilience and employment.
