Hands to Reclaim the Green City: The Beginning and Spread of Mandatory Rooftop Gardening in Kyoto (2007)

Hands to Reclaim the Green City: The Beginning and Spread of Mandatory Rooftop Gardening in Kyoto (2007)

Around 2007, Kyoto Prefecture and Kyoto City became the first in Japan to introduce mandatory rooftop greening. The law required newly constructed or reconstructed buildings with a site area of 1,000 square meters or more in urbanization zones to have at least 20% of their rooftop area greened. The background to this was the heat island phenomenon, which has become more serious since the early 2000s. Kyoto City's unique basin topography makes it easy for heat to accumulate in the city, and the increase in "tropical nights," when the temperature does not drop during the summer nights, has been affecting the lives of residents.

At the national level, from 2002 to 2004, the government formulated the "Outline for Urban Heat Island Countermeasures" to promote greening and high reflectivity. Based on this trend, Kyoto's system was realized as a local model integrating landscape preservation and global warming countermeasures. A lightweight greening base with high water retention properties was adopted, which was expected to improve the heat insulation performance of buildings and save energy.

Greening also spread to temple and shrine buildings, commercial facilities, and universities, integrating Kyoto's traditional landscape with environmental technology. The sense of mission as a signatory to the Kyoto Protocol also encouraged greening, which became a symbol of the "symbiosis of culture and the environment. Rooftop greenery not only mitigates the heat island effect, it has also become a symbolic landscape that brings the ancient capital back to life for the future.