In recent times, the world has undergone rapid urbanization and a surge in population growth, resulting in several environmental challenges. The proportion of the world’s population living in urban areas has dramatically increased from 30% in 1950 to 55% in 2018.

India is projected to have a manifold increase in urban population by the end of 2050. As the population density in Indian cities continues to grow, it becomes increasingly necessary to investigate various environmental issues affecting urban and rural areas.

One such environmental problem is the urban heat island effect, where a metropolitan area behaves as an abnormal island of high temperature compared to its surrounding rural regions.

This blog post will focus on explaining the heat island effect and its effect in Indian cities during summer.

Heat Island Effect: A Synopsis

The heat island effect is a comparative phenomenon that results from rapid changes in urban surfaces. It increases surface and air temperatures in the urban boundary area compared to the surrounding rural area.

Moreover, it can negatively impact human health, energy consumption, and the environment.

This effect is attributed to a combination of factors, including the absorption and retention of heat by buildings and pavement, reduced vegetation, the release of waste heat from cars and buildings, and so on. 
Types of Heat Island Effect

There are two types of urban heat island effects:

• Air urban heat island effect

• Surface urban heat island effect

Automatic weather station data measure the air urban heat island effect, while the surface urban heat island effect is measured using remote sensing sensors and aircraft.

The surface urban heat island effect boundary is defined by a sharp decrease in the land surface temperature along the urban-rural gradient.

A better understanding of the thermal characteristics of the urban environment can help us comprehend the surface urban heat island effect.

The urban heat island effect is a primary environmental concern for Indian cities due to its adverse impacts on human health, air quality, and the local ecosystem.

5 Major Causes of the Heat Island Effect in Indian Cities 

Here are some causes for the development of the heat island effect in Indian cities:

1. Urbanization 

Rapid urbanization has led to the conversion of natural shells such as woodlands, grasslands, and marshlands into heat-absorbing shells such as concrete, asphalt, and structures.

As a result, the quantum of heat absorbed by the metropolitan surroundings increases, leading to advanced temperatures.

2. Reduction in green spaces

As metropolises grow, there’s a reduction in green spaces similar as grounds, trees, and gardens. These green spaces help to reduce the heat island effect by furnishing shade and evaporative cooling, which helps to lower temperatures.

3. Industrial activities

The presence of industries and workshops in civic areas contributes significantly to the heat island effect. This conditioning releases large amounts of heat and adulterants into the atmosphere, leading to heat buildup and poor air quality.

4. Transportation

Motorized vehicles like cars and buses contribute significantly to the heat island effect. The vehicles emit heat and pollutants into the atmosphere, leading to higher temperatures in urban areas.

5. Building Materials

Using heat-absorbing structure accouterments like concrete and asphalt contributes significantly to the heat islet effect. These accouterments absorb and retain heat, leading to advanced temperatures in towns.

Effects of the Heat Island Effect on Indian Cities

Here are some effects of the heat island effect on Indian cities:

1. Energy Consumption

Summer days and nights, particularly in low-latitude metropolises, beget violent thermal discomfort and vexation to the civic population, raising the energy demand for artificial interior air cooling.

The urban heat island effect has grown a nature-fulfilling forecast as they’re both the cause and result of increased energy use in metro areas, creating a vicious circle of energy consumption and generation. 
2. Impact on Human Health and Comfort

The heat island effect in civic areas can bring heat-related ailments like heat fatigue, heat stroke, and dehydration. Vulnerable populations like children, seniors, and those with pre-existing medical conditions are at advanced threat.

Poor air quality from the heat islet effect can worsen respiratory problems and asthma, leading to increased hospitalizations and mortality. Also, rising temperatures can increase the growth of disease-carrying insects, adding to the threat of vector-borne conditions.

3. Impact on the Environment

The urban heat island effect can change the water cycle. The increased temperatures can accelerate evaporation rates, reducing soil humidity and adding water demand. It can pan out in an advanced threat of failure and water failure, particularly in towns where water resources are already under pressure.

The heat island effect can also have significant impacts on air quality. High temperatures can release adulterants from vehicles, artificial processes, and other sources, leading to poor air quality. Polluted air can bring respiratory problems and other health issues, not just for humans but also for indigenous wildlife.

Strategies to Mitigate Heat Island Effect in Indian Cities

Civic design dramatically contributes to the conformation of heat islands, and innovative growth development strategies can help reduce them.

Smart growth strategies help citizens make informed judgments about the constructed setting, leading to a more robust economy and healthier surroundings. Urban open spaces with suitable thermal terrain can attract citizens and boost town vitality.

The urban thermal environment is composed of air temperature, thermal radiation, wind speed, and humidity, and urban geometry affects radiative and convective heat transfer in outdoor spaces.

Compact spaces offer a better thermal environment than open spaces in hot climates. Vegetation reduces short-wave radiation and air temperature through transpiration.

Water bodies also reduce outdoor air temperature through evaporation and serve as heat sinks. Efforts to minimize heat islands can be practical when integrated into an approach that improves building performance, such as installing solar panels or vegetated roofs.

The Takeaway

Physical attributes that contribute to the development of the heat island effect in Indian cities like Mumbai, Pune, Delhi, Bengaluru, Chennai, and Kochi during summer include the high density of population, high-rise buildings, and the concentration of anthropogenic heat sources such as vehicular traffic, industrial activities, and air conditioning.

Also, the lack of foliage and vegetation, the use of heat-absorbing construction accouterments, and the civic figure that leads to reduced air rotation and limited shade complicate the heat island effect in these towns.

During summer, temperatures in these towns can reach as high as 40 °C. The heat island effect can increase the temperature by over 5 °C in urban areas compared to their pastoral surroundings. This temperature rise can lead to adverse health effects, including heat fatigue, heat stroke, and dehydration.

This is why Mechartés undertakes projects to study the urban heat island effect in Indian cities.

Our experienced consultants are adept at suggesting mitigation strategies to minimize the effects of heat island effect in Indian Cities during summer.

Contact our service advisors for more details.