InfraCivilCon2023: How to Make the Most of Strategic Green Spaces' Cooling Effects

One of the best and most accessible strategies to lessen the effects of rising temperatures in urban contexts is to use urban green spaces. Cities all across the world experience more frequent and severe heat waves, putting the lives of their residents at danger. Urban heat islands are created when natural land cover is replaced with surfaces that absorb and hold heat, such as pavements and buildings, and many cities are exploring methods to lessen their effects. In comparison to the surroundings, this causes the temperature to rise by a number of degrees. Cities have their own unique microclimate that is influenced by this phenomenon as well as a number of frequently disregarded elements. All elements must be taken into account for a climate plan to be effective.

The sociological makeup of the city is highly connected with heat risk levels. Less access to green spaces puts communities with historically underprivileged and less affluent sectors at higher risk. The impact on the underprivileged inhabitants can be decreased through land zoning and planning restrictions, increasing their health, wellbeing, and level of living. Improvements to the vegetation, according to scientists Winifred Curran and Trina Hamilton, may enhance property values and force long-term residents to leave. They advocate a "just green enough" approach that involves developing strategic initiatives to aid neighbourhood populations.

Urban warming cannot be solved by simply expanding "green coverage" without taking into account the relative position of green spaces. — Wan-Yu Shih, associate professor at Taiwan's Ming-Chuan University's department of urban planning and disaster management.

Controlling microclimates:

Although it is well established that green spaces can lower the average land surface temperature, their cooling effects are constrained. Most of the time, at a distance of more than 100 metres, these impacts are not noticeable. The topography and geometrical patterns of their surroundings can affect how far the cold air can go, as heat sources and physical structures frequently act as obstacles to airflow. As a result, increasing the percentage of green space without taking into account the local environment can only have a limited impact on lowering urban warming. Understanding these circumstances is essential to developing a successful plan of action in areas with a shortage of available space in congested metropolitan environments.

Streets with Trees

The microclimate of a city is significantly influenced by the street geometry. Their breadth and orientation impact the solar exposure of the nearby structures. Narrow roadways are advised in hot, dry conditions to ensure appropriate shading and prevent overheating. However, narrow streets can restrict airflow and obstruct natural ventilation channels, which is a factor that is crucial in humid climates. In contrast, wider roadways promote wind flow but also expose more of the surrounding buildings to direct sunlight at street level. Some of the negative consequences of roadway geometry can be effectively countered by placing trees along the streets. It has been discovered that the warming effect of the asphalt can be offset by a tree canopy that covers at least 40% of the area.