Can we cool our cities down?

Given the country’s hot weather conditions almost all the year, besides increasing urbanisation, and the worsening effects of climate change, managing ambient heat in Indian cities is a challenge. Nearly all aspects of urban lifestyles add to creating ‘hot’ cities — from the materials that we use for construction, to the use of fossil fuels for transportation — leading to our cities being hotter by 2 to 8 degrees celsius from the surrounding rural areas.

Urban areas are particularly vulnerable to the ‘urban heat island’ effect, where cities experience higher temperatures because of large areas without plantation and shade, and the ‘urban canyon effect’ due to dense packing of buildings that cuts out wind flow. The scorching temperatures, especially during the summer months, cause heat stress, posing significant health risks and compromising livability, making it imperative to adopt effective strategies for heat management.

Green facades

Implementing green infrastructure involves planning extensive green corridors, planted zones, and green facades as an integral part of the built environment. Planting trees along streets and establishing green rooftops and walls are some of the simple ways through which we can start the change. Trees provide natural shade, reduce heat absorption, and release moisture through transpiration, working as a potent strategy to cool surrounding areas.

The integration of greens within our cities should ideally be thought of at the planning level rather than just the building level. It needs to be integrated with an urban design strategy that takes into account prevailing wind directions and water bodies to create ‘green-blue’ connected corridors throughout the city. And this isn’t as difficult to do as it sounds. There is enough public land available in Indian cities which lies unused and can very easily be linked up to create these spaces. It needs careful mapping of ground situations with ownership maps to mark out such potential corridors.

Building regulations

Building and planning regulations are almost silent on environmental aspects. Enforcing building regulations that prioritise heat-resilient construction materials and designs is crucial. These regulations can also promote natural ventilation and shading techniques while limiting the usage of untreated glass. The focus of building regulations needs to shift from quantitative controls to more qualitative ones where consultative processes are used to improve urban environments.

We also need to allocate substantial budgets to take up urban schemes and enhance the technical expertise in local governance to direct and monitor climate strategies. The re-building of cities and their public realms to create cooler environments will be a slow and deliberate process that needs to be funded and supported through research.

Artificial ponds

Efficient water management is important to cool our cities. Rainwater harvesting, the creation of artificial ponds, and the rejuvenation of existing lakes can help maintain water resources and create cooling zones. Bodies of water act as natural heat sinks while also contributing greatly to groundwater replenishment.

Public transportation

Developing public transportation networks through efficient urban planning can reduce the number of private vehicles on the road. This not only decreases traffic congestion but also lowers heat emissions from vehicles, improving air quality and reducing urban temperatures.

Sustainable campuses

Our antiquated planning norms, which force single-use zones, are not the best way to plan cities. These must be replaced with mixed-use neighbourhoods, allowing for better-shared infrastructure use. Promoting compact, mixed-use layouts reduces the demand for sprawling road networks and parking areas. These designs also encourage walking and cycling, reducing the ecological footprint of campus transportation.

Integrated planning also allows for integrated infrastructure, reducing overall emissions. Concepts such as district cooling have already been effectively used in many parts of the world. District cooling uses a central plant to generate chilled water, which is then distributed through a network of underground pipes to provide air conditioning for various buildings. By using recycled water and by reducing the need for individual air conditioning units, such systems are an efficient solution to cooling large mixed-use developments.

Energy-efficient designs

Emphasising energy-efficient building designs can help reduce the heat generated by air conditioning systems. Orienting buildings correctly, allowing natural ventilation and analysing building design at a neighbourhood level will all help in significantly reducing temperatures. Promoting the use of cool roofing materials (whether planted roofs or roofs painted with heat-reflecting paints) is important as these surfaces absorb less heat, keeping indoor temperatures lower. Incentives and regulations to encourage cool roofing can make a great impact.

As our cities continue to grow at an unprecedented rate, we no longer have the luxury of space to go back to thick masonry construction which absorbs the heat. But there is enough research available to suggest alternative sustainable materials that are better at handling heat. These new materials and techniques (like prefabricated insulated boards, prefabricated structural elements) need to be showcased in some pilot projects to set off the change.

Managing heat in Indian metropolitan cities demands a multifaceted approach that combines sustainable urban planning, infrastructure development, and public engagement. It requires the coming together of multiple stakeholders, local bodies and knowledge-based organisations to work across different jurisdictions.

With the increasing threat of rising temperatures caused by climate change, these strategies are the need of the hour for creating cooler, more liveable cities.

The writer is Partner, team3.