The answer lies in fully utilising the knowledge of ‘the Cooling Web’ as well as traditional cooling methods
The world is experiencing record-breaking temperatures. July 2023 was recorded as the hottest month globally; in March 2023 India received its first heatwave of the year; and the World Meteorological Organization predicts there will be even hotter times in the next five years.
This means more and more air-conditioners to cope with the heat. This not only places a public health threat but upsets the energy budget of the country.
According to Niti Aayog’s India Energy Security Scenarios (2017), 65 per cent of the energy demand in buildings comes from space cooling and heating. This is only going to surge with increasing extreme weather events.
In 2019, India became among the first countries to launch a cooling action plan. Its targets include a reduction in cooling demand across sectors by around 25 per cent and a reduction in cooling energy requirements by around 35 per cent by 2038.
The plan also points out the need for non-refrigerant-based and not-in-kind technologies. What is interesting is the plan does not focus on just ‘sustainable cooling’, it has mooted the idea of ‘thermal comfort for all’.
This could be achieved by passive strategies like shading, ventilation, and insulation among others before adopting active/mechanical cooling measures.
Indian traditional architecture recognises that buildings need to respond to the native climate and geography. It has followed a bioclimatic approach to design and choice of materials.
Site planning, building form, envelope, materials, opening sizes even vegetation are all tweaked in response to the local context to achieve this bioclimatic design. This makes the occupant thermally comfortable with little or no dependence on active cooling measures.
This knowledge has been refined over generations to ensure the comfort of occupants in diverse thermal conditions and has come to us in heritage. The accumulated wisdom and adaptability have safeguarded India’s built environment from excessive reliance on mechanical cooling systems.
As a result, India maintains a remarkably low per capita space cooling energy consumption of 69 kWh per person, which is nearly four times less than the global average.
Environment, aspirations, and expectations all have changed. Cities have become denser. Vegetation and water bodies have decreased and we are producing more heat within our cities. This has affected the ambient temperature itself.
Centre for Science and Environment (CSE) is working on this issue, where we look at cooling on a city scale.
The other factor is that people’s idea of thermal comfort has changed, as quicker solutions to cooling have dominated the market, especially the incessant use of compressor-based air-conditioning. The repercussions are already showing in the form of huge energy penalties and human health impacts.
The combination of all these factors is expected to create a surge in cooling demand not just in India but globally.
The Ministry of Environment, Forest and Climate Change recognises this surge and estimates the cooling demand in buildings to grow 11-fold by 2037-38 when compared to the 2017-18 baseline.
The answer lies in fully utilising the knowledge of ‘the Cooling Web’. This web is looking at both, passive and active solutions that achieve cooling. More importantly, it also deciphers their chronology of application in the built environment.
The passive measures represent the strategies that enhance microclimate. This includes vegetation, water features, permeability, etc. and their relative placements in context with the built spaces, building envelope and material.
The interplay of these elements effectively brings up a desired thermal response, shading, ventilation and daylighting strategy for any building project.
This blend of context-appropriate design and technology has been documented by CSE in the form of multiple case studies. They represent a range of cooling solutions that are diverse and comprehensive and do not rely on conventional energy-guzzling practices.
These include:
1. Anil Agarwal Environment Training Institute in Neemli, Rajasthan. The campus has used a three-stage cooling system which includes indirect and direct evaporative cooling.
2. NIIT university Neemrana and Sabhakhand building inside Gujarat Vidyapith in Ahmedabad which uses the potential of earth to absorb heat by employing an earth air tunnel system.
3. IIT Gandhinagar in Gujarat and Indraprastha Institute of Information Technology in Delhi that use district cooling system and a ‘passive downdraft cooling’ system.
We need to reduce emissions and we need to learn to adapt to this changing climate. CSE will continue to research on what needs to be done and to advocate for policy and practice changes so that we can build wisely.
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