Heat stress, increased dependence on AC upset energy budget: study

The overall electricity demand in Delhi had dropped during the first phase of the lockdown, but recovered quickly to almost near-normal levels. This trend was largely driven by the heat stress and cooling demand in the residential sector, due to poor designing, according to an analysis by Centre for Science and Environment (CSE), a research and advocacy organisation in Delhi.

“Higher heat stress this summer combined with thermal discomfort in poorly designed buildings and increased dependence on air conditioning upset the energy budget,” says the CSE analysis.

The lockdown occurred during the summer and increased thermal discomfort hiked the demand for active cooling or air conditioning, the analysis said.

Anumita Roychowdhury, executive director-research and advocacy of CSE, said, “Understanding this connection is critical, as climate change will increase the frequency and intensity of heat waves in the future. If the built environment is not designed for thermal comfort, heat stress will increase cooling demand and use of energy-intensive mechanical cooling systems, thus undoing the carbon savings from other energy efficiency measures.”

Peak demands

The CSE said that the expectation was that the overall peak electricity demand during this summer would remain much lower than the peak demand of the previous summers. But in reality, though the average electricity demand through different stages of Lockdown and Unlock in 2020 was less compared to previous years, the margin reduced with increase in temperature.

For instance, in the first phase of lockdown the average daily mean electricity demand was lesser than 2018 and 2019 by 40-41%; the same was 35-37% during Lockdown phase 2 and 31-34% and 17-23% during phases 3 and 4.

“Every degree rise in heat index resulted in 187 MW increase in electricity demand during lockdown – this was 6 per cent higher than in 2019,” the CSE said in a statement.

“There should be a lot of attention to decrease the thermal load on buildings. We should encourage people to opt for adaptive thermal comfort such as good ventilation and reduce air conditioning hours,” Ms. Rowchowdhury told The Hindu.

The CSE said that architectural designs should be optimised to reduce heat load. This needs a quick operational framework to enable architectural design solutions, appropriate material, thermal load management, strategic and selective use of active cooling approaches and demand management measures to reduce the overall air-conditioned hours. Adopting guidelines, building byelaws, building-related energy regulations and good practices for an integrated approach are needed, it said.

Ms. Roychowdhury also said that India’s Cooling Action Plan, a policy document, has mentioned ‘thermal comfort for all’, but it has to be implemented by the government.

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Printable version | Oct 24, 2021 12:53:29 PM |

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