Delhi’s sweet spot: 25°C to 31°C

Study says power demand doesn’t rise with increase in temperature in this range

June 20, 2019 01:45 am | Updated 01:45 am IST - New delhi

The Centre for Science and Environment, in a study which is to be released on Thursday, has found that there is a temperature “sweet spot”, between 25 and 31 degrees Celsius, in which Delhiites are comfortable. In this range, the power consumption does not rise with increase in temperature, says the study.

The study analysed Delhi’s power consumption over the past eight years. “Electricity consumed on days when heat index was 25°C–31°C was observed to be unaffected by thermal stress (heat or cold),” the study states. Heat index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature.

The study also found that in summer months in Delhi, the peak power consumption during the night was more than the daytime, which showed that the peak power demand was driven by domestic consumption. It also found that the power demand in winter was driven more by the use of geysers than spacial heaters.

The study “A Midsummer Nightmare, Decoding the link between comfort, space cooling and energy consumption in a climate-stressed world”, written by Avikal Somvanshi, also found that there was a direct correlation between thermal discomfort and power consumption.

More demand at night

Thermal comfort is a state of human satisfaction to the thermal environment. “In Delhi, the peaks [power demand] are now more in night rather than at day, which is a weird behaviour. At this time, the commercial establishments are not working and this shows that the peaks is being driven by households. Though the overall consumption has always been more for households, the peaks were never driven by households,” Mr. Somvanshi said.

"During May (2018), for as many as 21 days, the late-night peak demand had been higher—up from 14 days in 2016,” the report states.

Explaining power consumption of January 2018, Mr. Somvanshi, said: “The power consumption starts picking up from around 4 a.m., when people start waking up. They switch on the geysers to get hot water for shower. The power consumption peaks around 10 a.m. and starts to dip at a time when most people go to office.” “This pattern doesn’t reflect use of space heaters, but that of water heaters.”

Thermal stress can be attributed 25%–31% of the total electricity consumed in Delhi in the last five years, according to the study.

The study also has a list of recommendations to reduce energy consumption. Mr. Somvanshi said that we need smarter building designs.


“Mandate sunshades for all windows and make a provision for installing desert coolers in all new housing. Builders have resorted to providing only ACs in new buildings, making it difficult for people to use any other means of cooling,” the report states. “Run aggressive market awareness campaigns on multiple benefits of energy-efficient buildings, such as reduced operational costs, health and comfort, environmental and societal benefits,” reads another recommendation.

Mr. Somvanshi said that the Bureau of Indian Standards has been directed by the Centre to come up with comfort standards. “Unless we have these comfort standards for summer and winter and regulate unnecessary cooling, we will be wasting energy. We keep designing buildings which are driven by comfort standards of the AC industry, which is not trying to help us, but make profit,” he said.

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