Eco-City Innovations:  Urban Design for a Cooler Tomorrow

5/31/2024
Melissa Maliyil (Hebron High School)

One of the first words that comes to mind when thinking of giant, sprawling cities is “hot.” There is a reason for the significantly warmer temperatures of these areas: the Urban Heat Island (UHI) effect. It is the tendency for urbanized areas to be much hotter than the areas surrounding it due to an increased amount of heat being absorbed by all the buildings and roads combined with the lack of greenery. This can cause temperatures to be up to 7 degrees Fahrenheit hotter in the city compared to surrounding areas. The Urban Heat Island effect poses several consequences for both people and the environment. It can increase the amount of energy consumption because for every 2 degrees hotter the city gets, almost 10% more energy is required to keep a building cool. 

Addressing this issue is crucial for creating more livable urban environments. It causes increased daily temperatures, higher temperatures at night, and increased air pollution. These can then lead to more heat-related health issues such as heat stroke, respiratory difficulty, and other concerning things. There are various construction techniques that can help reduce the UHI effect, including green roofs, cool roofs, urban green spaces, reflective and permeable pavements, and strategic urban planning.

One of the most popular strategies to minimize the UHI are green roofs. Green roofs are an extension of existing roofs covered with vegetation. They consist of several layers, including a waterproof membrane, soil, and plants. Green roofs help cool buildings by providing insulation, reducing the need for air conditioning. The plants also absorb sunlight, which reduces the amount of heat that the building and surrounding areas absorb. Additionally, green roofs release moisture into the air through a process called evapotranspiration, which helps to cool the environment. Cities such as Chicago have been massively successful in implementing green roofs, as it has over 5,564,412 square feet of green roof coverage.

Similar to their green counterparts, cool roofs are designed to reflect more sunlight and absorb less heat than standard roofs. They achieve this by using reflective coatings or light-colored materials. By staying cooler in the sun, these roofs help to lower the temperature inside buildings and reduce the overall heat that urban areas accumulate. Normal roofs can reach up to 150 degrees Fahrenheit on particularly sunny days, but these reflective alternatives can lower temperatures by up to 50 degrees. Cool roofs can significantly cut down on energy costs by decreasing the need for air conditioning. 

Another solution many cities use are urban green spaces, such as parks and green belts, which play a crucial role in mitigating the UHI effect. Beginning as “lungs for the city” in the nineteenth century, trees and plants in these areas provide shade and cool the air through evapotranspiration. The strategic placement and distribution of green spaces can enhance their cooling benefits. For example, placing parks in densely built-up areas can create cool islands that help lower surrounding temperatures. Cities like New York have successfully integrated green spaces into urban planning, with programs such as Million Trees NYC investing $82 million dollars in planting trees across streets in the city. 

Likewise, reflective pavements are made from materials that reflect more sunlight and absorb less heat, similar to cool roofs. This helps to reduce the amount of heat stored in urban surfaces. Permeable pavements, on the other hand, allow water to seep through and be absorbed by the ground. This not only reduces runoff but also cools the pavement as the water evaporates. Both types of pavements can significantly lower the UHI effect by decreasing heat absorption and promoting natural cooling processes. Tokyo is a great example of this, where 96 kilometers of reflective pavements have reduced surface temperatures almost 15 degrees Fahrenheit and 20 kilometers of permeable pavements have lowered possible surface temperatures 18 degrees Fahrenheit. 

In conclusion, various construction techniques can effectively mitigate the Urban Heat Island effect. Green roofs, cool roofs, urban green spaces, reflective and permeable pavements, and strategic urban planning all contribute to cooler, healthier urban environments. Combining these methods can amplify their impact, making cities more resilient to heatwaves and improving the quality of life for their residents. As urbanization continues to increase, it is essential for cities to adopt these strategies to create sustainable, livable spaces for future generations.