I had the opportunity to present the 3-30-300 rule during a program on urban cooling strategies in Montpellier produced by France 3 Occitanie.
This rule was invented by Dutch researcher Cecil Konijnendijk, who specializes in urban forests.
This is a simple design rule that was designed to improve the quality of life and well-being of city dwellers by encouraging the planting of green spaces.
This 3-30-300 principle breaks down as follows:
Every city dweller must have a view of at least 3 adult trees from their home.
Every city dweller must be in a neighborhood or town with at least 30% tree area.
Every city dweller must live less than 300 meters from a green space.
The effectiveness of the 3-30-300 rule on the psychological development and mental health of urban residents has been documented and proven by certain studies.
This simple principle is also interesting for combating the urban heat island (UHI) phenomenon.
Indeed, there is a threshold beyond which the size of a park has relatively little influence on urban cooling on its periphery.
The 3-30-300 rule requires the design of small, compact green spaces scattered within the urban fabric, like squares.
This provision is a priori much more effective in terms of combating the urban heat island.
In addition, the effectiveness of tree cover greater than or equal to 30% for urban cooling has also been studied, as I discuss in the video.
The simplicity of this rule should not, however, overshadow the constraints that weigh on the planting of trees in the city (soil, watering, exposure, maintenance, etc.).
But for once there is a simple and scientifically based rule, we might as well share it!
Source: C. Konijnendijk
Image: Unsplash, Stephanie Davison