CSE releases new analysis of electricity consumption in Delhi during the lockdown and un-lockdown phases
When the COVID-19 triggered lockdowns had brought the economy to a near halt, overall electricity demand in Delhi, after an initial drop during hard lockdown 0.1, recovered quickly to almost near-normal levels – says a new analysis by Centre for Science and Environment (CSE) on the electricity demand and correlation with weather data during the successive stages of lockdown and unlocking in Delhi. This trend was largely driven by the heat stress and cooling demand in the residential sector.
“Higher heat stress this summer combined with thermal discomfort in poorly designed buildings and increased dependence on air conditioning upset the energy budget. Every degree rise in heat index resulted in 187MW increase in electricity demand during lockdown – this was 6 per cent higher than in 2019,” says the CSE analysis.
The lockdown occurred during summer when heat waves lash Delhi. Increased thermal discomfort increased the demand for active cooling or air conditioning.
Says AnumitaRoychowdhury, executive director-research and advocacy, CSE: “Understanding this connection is critical, as climate change will increase the frequency and intensity of heat waves in the future. If 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.”
Roychowdhury says that according to the World Energy Outlook of the International Energy Agency, cities account for nearly 70 per cent of the global consumption of electricity.
In its study, CSEcarried out a rapid analysis of real-time electricity demand during the lockdown and unlocking phases in Delhi. CSE accessed real-time electricity consumption data of 5-minute granularity from the State Load Dispatch Center in Delhi, the apex body responsible for integrated operations of Delhi’s power system. It has also accessed weather data of 15 minute granularity from the continuous ambient air quality monitoring (CAAQM) stations that are reported by the Central Pollution Control Board (CPCB).
The analysis has considered the following time slots: Pre-lockdown – 1 January to 21 March, Lockdown 1.0 – 22 March to 14 April; Lockdown 2.0 – 15 April to 3 May; Lockdown 3.0 – 4 May to 17 May; Lockdown 4.0 – 18 May to 31 May; Unlock 1.0 – 1-30 June; and Unlock 2.0 – 1-31 July. Wherever applicable, comparison with pervious years have been indicated.
Says Avikal Somvanshi, programme manager with CSE’s Urban Data Analytic Lab, says: “Delhi is a big energy guzzler and makes an important case study. CSE’s earlier analysis in 2018 and 2019 had found that Delhi’s peak electricity demand was consistently higher than Mumbai, Kolkata and Chennai taken together. Delhi’s appetite for electricity has almost tripled since 2000. Domestic and commercial consumers together accounted for almost 75-80 per cent of annual electricity consumption in Delhi during the period 2010 to 2017. On an average, an electrified household in Delhi consumed about 260 kWh of electricity monthly in 2016–17, that were up from 155 kWh in 2000, which is almost three times the national figure of 90 kWh.”
Key highlights of the findings
- Overall demand for electricity dropped during complete lockdown, but bounced back quickly: Overall electricity demand during the severe lockdown dropped substantially compared to the corresponding time in the previous years and the pre-pandemic times. But it also bounced back substantially with partial reopening and higher heat stress during the un-lockdown phases.
On the eve of the Janata Curfew (22 March), the average electricity demand dropped by 23 per cent (563 MW) compared to the pervious day – 21 March, or by 18 per cent (426 MW) if compared with the previous Sunday (15 March) which is also a holiday.During the lockdown phases the lowest demand (1,748 MW) was recorded on 29 March – just before the onset of high summer. It rose to over 4,000 MW by end of May, the high summer, – thus, the demand more than doubled within the lockdown period and with small reopening of the economy in the later part. During the unlock phases the average daily demand further increased. It was only 10 per cent lower than the corresponding period in 2019.
One would have expected that the overall peak electricity demand during this season would remain much lower than the peak demand of the pervious summers. But it is interesting to note that the daily average demand hovered around 4,000 MW during most of unlock phases with limited reopening. The season’s highest average (5,287 MW) and peak (6,305 MW) were recorded on 3 July. During the last couple of years the seasonal high have also been recorded pretty much around the similar dates. But it is notable that the peak level recorded during this summer was just about 10 per cent lower than 2019’s high of 7,372 MW.
It is also notable that the overall reduction was not that dramatic even though there was mass exodus of migrant workers and their families from the city that started during lockdown 2.0 and continued through lockdown 3.0 and lockdown 4.0. It has been reported that about 7-8 lakh migrants had left the city that implies less active households in Delhi in that timeframe. Despite this, city’s overall demand for electricity increased substantially. Migrants are small users of electricity. This also validates the class disparity in electricity consumption in the city and reinforces whose summer demand and needs of cooling is responsible for city’s voracious appetite for electricity.
- Despite the lower economic activities, heat stress made electricity demand bullish: This year, lockdown reduced the total overall demand but the trend with heat index remained the same as previously seen. Explosive rise in electricity demand was delayed by a few degrees and started when daily mean heat index crossed 27-28°C. Every degree rise resulted in 187 MW increase in electricity demand during lockdown, this was 6 per cent higher than 2019.
When the heat wave lashed towards the end of May lockdown (24-27 May) economic activities were restored slowly but the level of activity was still way below the normal levels of corresponding period in 2019 and 2018. But even with lower level of economic activities, both daily average and peak demand in the city were higher than the levels recorded on the same dates in 2019 and 3 per cent lower on same days in 2018. This shows that the change in heat stress and lack of thermal comfort can influence electricity demand substantially even if economic activities remain sub-optimal.
- Night-time energy peak bears out the disproportionate impact of residential cooling demand: During lockdown and economic slow down night-time (midnight to 4 am) electricity demand remained more obstinate and high. During lockdown, every degree change in daily mean heat index (influenced by weather paramerters including temperature, humidity etc) led to over 225 MW change in average nighttime demand. It is about 6 per cent lower than 2019. But it is about 20 per cent higher per degree increase computed for whole day (midnight to midnight) during the lockdown.
When heat wave lashed in May, night-time peaks were consistently higher than afternoon peaks. Lockdown 4.0 was marked by a short heat wave that started on 24 May with ambient temperature hitting 47oC on 26 May. It ended with rains on 28 May. By this time afternoon peak had developed mostly due to opening of some commercial activities and also due to increased heating of building envelopes. During the heat wave episodes night peaks were significantly higher than afternoon peaks. This reflects the high demand for active cooling. Even at themoderately lower range of heat index the nighttime demand increased faster than the whole day demand. This shows that threshold tolerance level of thermal comfort for sleeping is lower than that needed for daytime activity.
- Peak energy demand during afternoon flattens, shifts to night-time during lockdown: There was no visible afternoon peak during the first two phases of lockdown. During the previous years night peak and afternoon peak have been comparable with one edging out the other with smallest of margins.During the hard lockdown phase, afternoon peak was registered only once — thus the number of days with high afternoon peak is down from 29 days in 2019 summer to just one day during this summer. Afternoon peak started to develop by the end of lockdown phases but even then nighttime peak dominated 51 out of 60 days during the unlocking phases.
It is likely that the commercial and retail establishments were closed and did not contribute towards peaking during the day. But ‘work from home’ has also not impacted the daytime residential electricity consumption to that extent. Air conditioning for work at home should ideally have overtaken or at least be equal to the night peak. But data indicates that people likely to have not turned on their AC during the daytime as much as they did during night. They seemed to have relied more on adaptive thermal comfort approaches during the day preferring higher level of comfort during night and resorted to more selective use of air conditioners.
While this trend needs deeper investigation, it is notable that active cooling is expensive and household budgets cannot sustain infinite use of air conditioners as is possible in offices. It is also likely that the controversy around the role of air conditioner in making the virus thrive in ducts and on cooled surface restrained usage to some extent leading to more selective usage. These factors may have contributed to influence the day-time demand pattern. But this needs more investigation and is beyond the scope of this analysis.
- Cooler rainy days prove the importance of designing well-ventilated buildings to reduce active cooling or air conditioning hours: During the pandemic period there were days that experienced intense showers. Thunderstorm on 29 June knocked down the ambient temperature by 11°C (HI 17°C) between 4-7pm. This led to an almost instant drop in city’s electricity load from 6,234 MW to 3,844 MW. This amounts to 38 per cent drop in just 3 hours. This indicates that people could experience improvement in thermal comfort due to lowering of heat stress and also leverage the openings and windows to access cooler air outdoor to improve comfort conditions and reduce the need for active cooling.
- Impact of lighting requirement on electricity demand: The lockdown phase also created a unique opportunity to understand the impact of lighting requirement on electricity demand. This opportunity came on April 5, 2020, when all households across the city switched off domestic lights at 9pm to express solidarity with nation’s fight against the pandemic. Delhi’s power demand fell to 1,257 MW at 9:10 pm from 1,960 MW at 8:50pm. The demand returned to normal cycle by 9:45 pm. There was a drop of 703 MW in 20 minutes. This is the best measurement of active artificial lighting load of the city till date. This roughly translates into 10 per cent of city’s nighttime peak load. In fact, if evening peak is considered lighting can make up about 20 per cent of that peak. In fact, lighting demand dominates peak during fall and spring seasons when space-cooling or space-heating requirements are minimal or non-existent.
The way forward
This analysis has helped to understand the pattern of electricity demand in Delhi when influence of diverse set of economic activities are controlled and removed. This has helped to isolate the pronounced influence of residential demand and response to heat stress. The overall level of electricity demand reduced during hard lockdown; but with partial unlocking and even with much lower level of economic activities, heat waves combined with thermal discomfort in poorly designed buildings spiked the peak demand again – taking it quite close to the peaks of previous summers.
Says Roychowdhury: “There is a message for the post-pandemic ‘new normal’. The learning from the lockdown phases challenge the current approaches that predominantly focus on energy efficient cooling systems and do not pay adequate attention to the architectural design and material and heat management strategies to reduce the overall thermal load on buildings and the city.”
But Delhi and rest of India have an opportunity in the dominance of mixed mode buildings that combine mechanical cooling and passive cooling through ventilation etc. People have higher thermal tolerance and take advantage of improvement in weather conditions by leveraging windows and openings. This demands immediate strategy to design thermally comfortable building and promote adaptive thermal comfort and reduce air-conditioned hours in a year.
What CSE recommends:
- Optimise architectural design to reduce heat load and operationalise thermal comfort for all: India’s Cooling Action Plan (ICAP) has already provided for ‘thermal comfort for all’. But this requires 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. Adopt guidelines, building byelaws, building related energy regulations and good practices for an integrated approach.
Promote adaptive thermal comfort standards and passive design interventions.
Adopt a Bush Shirt Rule to allow people freedom to dress for comfort at work and for formal engagements.
- Need inclusive approach towards thermal comfort: Already policies and programmes related to affordable housing sector (both formal and informal self-construction as well as rental housing) have started to get financial support as in the case of PrashanMantriAwasYojana. It is important to link government funding and support with performance indicators related to thermal comfort requirements to promote passive cooling design for economically weaker section.
- Retrofit existing buildings to enhance thermal comfort and reduce operational energy need:Retrofit and retro-commission existing buildings to improve their thermal comfort performance and to reduce their cooling requirements and energy consumption.
- Need heat action plan to reduce urban heat island effect and heat stress: Develop and implement heat action plans in cities to control heat island effect from concrete and built environment. Also adopt urban heat-reject management plan to minimize impact of waste heat being ejected into the environment by mechanical systems like air conditioning operating in a city.
- Need awareness building: Run aggressive market awareness campaigns to sensitize both the construction community as well as the end-users towards the multiple benefits of energy-efficient buildings—reduced operational costs, health and comfort, environmental and societal benefits.
By Ms. Pratyusha Mukherjee, an active Journalist working for BBC and other media outlets, also a special contributor to IBG News & IBG NEWS BANGLA. In her illustrated career she has covered many major events.