Date Published: October 23th, 2023
Written by: Annisa Sabran, edited by Irvan Tadaru, Hanif Shidki, Mubashir Moqeem
How planting trees can reduce the effect of the urban heat island?
If you live in a city, you might have noticed that it is often hotter than the surrounding countryside. This is because of the urban heat island effect, which is the phenomenon of higher temperatures in urban areas due to human activities and the lack of vegetation.
Nearly 40% of deaths due to urban heat island could have been prevented if urban tree cover were increased up to 30%.
An urban heat island means that an urban area or metropolitan area is significantly warmer than its surrounding rural areas due to human activities. The urban heat island effect is caused by the building materials like concrete and asphalt which can absorb and trap heat, causing serious consequences for our health, environment, and economy. It can increase the risk of heat-related illnesses, worsen air quality, increase energy demand for cooling, and contribute to climate change. But there is a simple and natural solution to this problem: choose an Environmentally Sustainable Design (ESD).
One of the effective methods to integrating Environmentally Sustainable Design (ESD) into urban design and planning can be done through vegetation, landscaping and planting more trees.
Trees are amazing at cooling down our cities for several reasons. First, they provide shade, which reduces the amount of solar radiation that reaches the ground and buildings. This lowers the surface temperature and reduces the need for air conditioning. Second, they evaporate water through their leaves, which cools the air and increases humidity. This process is called evapotranspiration, and it can reduce the air temperature by several degrees. Third, they filter the air by absorbing pollutants and releasing oxygen. This improves the air quality and reduces greenhouse gas emissions.
Examples of Tree Planting Word-Wide
Seoul, South Korea has created “wind path forests” to circulate clean air, absorb particulate matter and minimize the urban heat island effect. Liverpool, United Kingdom has installed a living wall which would trap pollution but also the home of beehives ready to pollinate the city.
Curitiba, Brazil has planted 139,000 trees alone between 2013 and 2016. Singapore as part of their Green Plan 2030 is planning to add 400 parks and 4 nature reserves. Izmir, Turkey has created tiny parklets with large effects for air quality of the city.
Case Study of High City-Wide ROI: Jakarta, Indonesia
Jakarta, with a population of 28 million in its greater metropolitan area, is the world’s largest city without a metro system. It is also infamous for its severe traffic congestion, which results in high levels of emissions from vehicles. Additionally, the burning of forests and agricultural land in the surrounding region exacerbates the problem by adding smoke to the already polluted air. These factors contribute to dangerous levels of particulate matter (PM) in the air, not only in Jakarta but also in the neighboring areas.
Although the Indonesian government has implemented measures to curb pollution and prevent illegal burnings, tree planting initiatives could still yield significant benefits for Jakarta, particularly in terms of reducing PM levels. By investing just US$4 per person annually, over 4 million people in the city could experience significant reductions in temperature and PM levels.
How to Incorporate Trees into Urban Design?
Here are some types of urban tree planting strategies that can be incorporated into the cities for reducing the effect of urban heat island:
1. Green Roofs
Green roofs are rooftops that are covered with vegetation, such as plants, grass, or trees. They have many benefits for the environment and human well-being. Green roofs can:
- Reduce the urban heat island effect by lowering the temperature of the roof and the surrounding air
- Save energy by providing insulation and shading for buildings
- Manage stormwater by retaining and filtering rainwater
2. Vertical Greenery
Vertical greenery is the practice of growing plants on the vertical surfaces of buildings, such as walls, balconies, or windows. It offers various advantages for the environment and human well-being. Vertical greenery can:
- Beautify cities by creating green spaces that improve the visual appearance
- Enhance air quality by filtering pollutants and producing oxygen
- Increase biodiversity by creating habitats for wildlife, such as birds, insects, and small mammals
3. Green Pavements
Green pavements reduces the amount of artificial material on urban pavements through replacing it with natural soil elements with grass. They are made of permeable or porous materials, such as pervious concrete, porous asphalt, or pavers. Green pavements have many benefits for the environment and human well-being. Green pavements can:
- Reduce flooding and erosion by increasing the infiltration and storage of rainwater
- Recharge groundwater and protect water quality by filtering pollutants and reducing runoff
- Improve aesthetics and comfort by creating natural-looking and soft surfaces
4. Infrastructure Greenery
Infrastructure greenery is the practice of adding plants and trees to existing urban infrastructure, such as bridges, tunnels, highways, and bus stations. It has many benefits for the environment and human well-being. Infrastructure greenery can:
- Reduce the urban heat island effect by cooling the infrastructure and the surrounding air
- Improve air quality by filtering pollutants and producing oxygen
- Improve aesthetics and comfort by creating green spaces and reducing noise
5. Green Parking Lots
Green parking lots reduces the amount of artificial material on parking lots through substituting it with ground vegetation (natural soil and grass) and/or trees and other vegetative infrastructure. They can reduce stormwater runoff, lower the urban heat island effect, improve air quality, and enhance biodiversity. Green parking lots can:
- Plant trees and vegetation to provide shade, evapotranspiration, and air filtration, which can cool the pavement and the surrounding air
- Install solar panels or wind turbines to generate renewable energy for lighting and electric vehicle charging
- Encourage alternative modes of transportation, such as walking, biking, or public transit, by providing bike racks, bus stops, or carpool spaces
Eco Mantra: Creating Eco-Friendly Destinations and Experiences
Eco Mantra is an environmental engineering consultancy that specializes in sustainable design and development of properties. Our goal is to create eco-friendly destinations and experiences that respect and restore the local environment, while also enhancing the performance and well-being of the users. To achieve this, we implement various microclimate strategies that are suitable for the local context, such as using porous paving blocks and local native plants. These strategies can help reduce the urban heat island effect, conserve water, and enhance biodiversity. One of our projects, Somewhere Lombok, showcases these strategies in action. Eco Mantra believes that building in nature and with nature can create a positive impact on the environment and society.
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