Do you feel like the asphalt is suffocating you every summer? It’s not your imagination; in fact, it’s a very specific effect with an equally specific name: it’s called the heat island effect.Madrid has a problem with concrete, but there’s an almost mathematical formula to solve it.
Squares like Puerta del Sol and Santa Ana have prioritized concrete, forcing pedestrians to seek shelter during the cooler hours—or under awnings that only appear in summer.
But when there are no awnings, a question arises: how many trees are needed? The answer lies in a simple, easy-to-remember rule that establishes the minimum requirements for a city to be healthy. It is known as the 3-30-300 rule, and if applied, it would transform the way we live in Madrid.
The 3-30-300 rule: the guide to a healthier city
The formula was coined by Cecil Konijnendijk, a Dutch professor and expert in urban greening. He proposes three basic requirements: that every citizen can see at least three trees from their window, that they live in a neighborhood with 30% vegetation cover (the shade cast by tree canopies), and that they have a park or green space no more than 300 meters from home.
These criteria, endorsed by Greenpeace in its 2021 report “Greening Cities,” amount to about 50 m² of green space per resident. Madrid, however, offers only about 21 m² per resident, and this is distributed very unevenly across districts. While some areas enjoy parks, others are veritable “heat islands.”
The debate has intensified following controversies such as the felling of trees in Plaza de Santa Ana or articles like the one in The Guardian, which asked why the capital is reducing its tree cover when summers are getting hotter and hotter.
More trees, better health
Living in a more natural environment has a direct impact on well-being. The Greenpeace report details how green spaces help mitigate high temperatures and the risk of flooding, in addition to acting as natural air filters and promoting biodiversity. On a personal level, the benefits are even greater.
It has been proven that contact with vegetation improves mental health, reduces stress and fatigue. It also enhances cognitive function and lowers the risk of disease and premature mortality. In short, living near green spaces makes us healthier and happier.