Heat islands refer to urban areas with higher temperatures than the surrounding regions. The question is, how are these heat islands formed? Are they a recent development, or have they been around for some time? Heat islands are a result of using less permeable building materials and construction methods. Urbanization plays a significant role in altering climatic conditions, leading to higher temperatures in urban areas compared to less developed areas. The construction and use of building materials contribute to the absorption and retention of heat, exacerbating the issue. However, by utilising high-albedo materials, the amount of solar radiation absorbed by buildings can be reduced. These issues are increasingly pressing for metropolitan cities.
Types of Urban Heat Island (UHI)
Surface Urban Heat Islands (SUHIs) and Atmospheric Urban Heat Islands are the two distinct categories of urban heat islands. SUHIs are assessed using land surface temperature (LST). Estoque’s research focused on SUHIs, establishing their persistent presence throughout both day and night, with peak temperatures occurring during daylight hours due to solar radiation. An independent study conducted by the US EPA 2008 examined a multitude of landscape variables to comprehensively elucidate regional variances in surface temperatures. The findings of these studies have significant implications for landscape and urban design, as well as broader SUHI research endeavours.
Apart from these types, there are basic factors behind this urban heat island effect like heat generated from the vehicles also add heat to the environment. Skyscrapers are also one of the reasons that heat formation expands in urban areas. The construction of skyscrapers is defined as a heat escaping zone where it does not get the path to release.
Evapotranspiration
The name itself consists of two meanings: evaporation and transpiration where evaporation refers to the movement of water to the air and transpiration refers to the movement of water in a plant. Therefore, trees are a must for reducing the higher temperature in urban regions which further can be reduced in two ways- first, through shadow, defined as solar radiation absorbed by leaves. Second, the cooling process of the environment is termed evaporation.
Strategies
Various strategies can help to reduce the urban heat island effect. One strategic approach is to use lighter colour materials that absorb less solar radiation. Applying lighter colours on roofs provides an idea of cool roofs. Additionally, reflective coatings that absorb visible light while reflecting invisible light can be used. The use of solar panels is also an effective solution for reducing solar radiation. Green roofs, which entail covering rooftops with plants, are another excellent approach to reduce building heat gain. Combining green roofs with permeable paving surface materials can further help in reducing urban heat island effects, leading to enhanced green parking lots in urban areas. Providing shaded pathways with tree covers can minimise the amount of radiation absorption. Maintaining water bodies in metropolitan locations might be difficult, but it can help to chill the climate. Implementing good and sensible landscape techniques also proves to be very helpful in reducing the urban heat island effect.
An excellent example of effective implementation of these strategies is seen in Dayalbagh, Agra. Located about five kilometres away from the city centre, on entering the periphery of this region, people can automatically feel the temperature difference. One of the major reasons for this is Evapotranspiration, a technique that helps save the whole society from higher solar radiation on the hottest days of summer. Dayalbagh follows the Sigma Six Q model, a sustainable model, and is referred to as an eco-village due to its excellent use of traditional and vernacular techniques in a sensible way, aiming to regenerate and restore its social and natural environments.
“This is the Dayalbagh way of life – Sigma Six Q.
Sigma means that all these aspects or components have
interaction amongst themselves and the cumulative
effect of all these is many times more than their
individual effect”
-Revered Prof. Prem Saran Satsangi
Dayalbagh is a self-sustaining society with substantial agricultural production, water harvesting, and highly renewable solar energy. The village is equipped with educational institutes, schools, and hospitals, and all have been constructed with sustainable materials. Rainwater harvesting has been effectively implemented, along with a proper sewage system and garbage disposal and treatment facilities.
Dayalbagh practises a combination of traditional and modern agricultural techniques and also has Gaushala and dairy facilities. The presence of flora in this location helps to keep it cooler than other parts of the city. The greenbelt is critical to the settlement’s meticulous planning. Dayalbagh’s west side includes extensively covered triangular areas that extend to the Yamuna River. Electric cars and rickshaws transport residents of the Dayalbagh colony to limit the number of fossil-fuel-powered vehicles in the area. Dayalbagh has evolved into a centre of great spiritual, scholastic, and moral values, offering consolation, satisfaction, calm, and enlightenment to its residents as well as visitors who come in droves seeking inner and exterior peace.
Reference list:
Sigma Six Q&Vs: Making Sustainability a Way of Life, Sigma Six Q
Available at: http://sigmasixq.blogspot.com/2019/04/dayalbagh-eco-village.html. [Accessed: 08 July 2024]
Urban heat island – causes, impact and solutions: Explained, Pointwise, Forum IAS
Available at: https://forumias.com/blog/urban-heat-island-and-its-impact/ [Accessed: 08 July 2024]
Urban Heat Island Mitigation, Cool Roof Rating System
Available at: https://coolroofs.org/resources/urban-heat-island-mitigation [Accessed: 07 July 2024]
Fadhil, M., Hamoodi, M., Ziboon, A. (2023). Mitigating Urban heat island effects in urban environments: strategies and tools, IOP Conference Series: Earth and Environmental Science
Available at: https://iopscience.iop.org/article/10.1088/1755-1315/1129/1/012025/meta [Accessed: 11 July 2024]
