Oct 9, 2019 - Energy & Environment

Green rooftops surge in popularity and offer environmental benefits

A green rooftop filled with plants.

Photo: Xavier TESTELIN/Gamma-Rapho via Getty Images

Green rooftops are growing in popularity, offering a slew of environmental benefits, the New York Times reports.

The big picture: The rooftops on apartments or commercial buildings often feature lawn areas, grills and seating. Some host community gardens, blossoming vegetables and herbs. But the greenery, and corresponding absence of asphalt and shingles, doesn't just up the aesthetic, it lowers surrounding temperatures, reduces energy use and assists in filtering storm water.

  • Green Roofs for Healthy Cities estimates the rooftops in North America have increased roughly 15% since 2013.
  • The National Research Council of Canada estimated the rooftops can lower a building's air conditioning use up to 75%.
  • Plants on rooftops are able to absorb rain water before it hits the ground, acting as filters and reducing runoff.
  • And, through evapotranspiration, plants cool the surrounding air by evaporating moisture, allowing temperatures to cool.

Between the lines: In many cities, the rooftops are no longer optional.

  • Both New York City and San Francisco have passed requirements for newly constructed buildings to have some component of green roofs, solar panels or both.
  • In 2010, Copenhagen made green roofs a requirement for all new commercial buildings, with a caveat for those with over a 30-degree slope.
  • In 2016, Córdoba, Argentina, passed legislation requiring all rooftops over 1,300 square feet, regardless of age, to turn green.

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