Estimating the environmental effects of green roofs

A case study in Kansas City, Missouri


A green roof—also called a vegetated roof or eco-roof—is a roof with soil and plants placed on top of a conventional roof. Green roofs are growing in popularity, as they have proven to be a cost-effective strategy for creating more livable and sustainable cities.1 Integrating nature-based solutions like green roofs into the urban landscape can benefit the environment, public health, and society by:

  • Reducing stormwater runoff.
  • Lowering ambient air and surface temperatures and reducing the urban heat island effect.2,3
  • Increasing building efficiency and reducing energy use for heating and cooling.4
  • Reducing air pollution associated with heating, electric power generation, and temperaturedependent formation of ground-level ozone.5
  • Achieving health benefits associated with reducing fine particulate matter (PM2.5) air pollution.
  • Improving psychological well-being through access to nature.6

This case study uses the Kansas City metropolitan area, and specifically the city of Kansas City, Missouri (KCMO), to demonstrate the environmental and health benefits of green roofs. Companies and municipalities are increasingly turning to nature-based approaches like green infrastructure to help protect people and infrastructure from extreme temperatures, severe storms, and chronic droughts. For example, city planners and stormwater managers are implementing green roofs and other green infrastructure practices as a cost-effective way to manage stormwater where it falls, reducing polluted runoff and keeping excess stormwater out of the sewer system while also creating a community amenity. By 2020, green roofs in KCMO could retain 29 inches of annual stormwater runoff if building developers and parking garage owners continue to install green roofs at the current growth rate. The intended audiences of this case study are city planners, regional planning organizations, nonprofits, environmental staff in governors’ offices, and other state or local officials who want to learn about and be able to demonstrate that green roofs have multiple environmental benefits: providing stormwater management during wet weather events, lowering ambient air temperatures on hot summer days, and cleaning the air. This information may also be useful for stormwater management plans, for meeting National Pollutant Discharge Elimination System permitting requirements, or for Air Quality Management Plans, such as those that may be developed under EPA’s Ozone and Particulate Matter Advance Programs.

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