Kumar Biswajit Debnath

Rural self-constructed homes in China’s cold-temperate regions often exhibit poor energy performance due to limited budgets and substandard construction, leading to a high reliance on active systems and low climate resilience. This study assesses four passive cooling strategies, nighttime natural ventilation (NNV), envelope retrofitting (ER), window shading (WS), and window-to-wall ratio adjustment (WWR), under 2040–2080 representative future climate conditions using energy simulation, multi-objective optimization, sensitivity analysis, and life-cycle cost assessment. Combined measures (COM) cut annual cooling demand by ~43% and representative peak cooling loads by ~50%. NNV alone delivers ~37% cooling reduction with rapid payback, while ER primarily mitigates heating demand. WS provides moderate cooling but slightly increases winter energy use, and WWR has minimal impact. Economic and sensitivity analyses indicate that COM and NNV are robust and cost-effective, making them the most suitable strategies for low-energy, climate-resilient retrofits in cold-climate rural residences. Since statistically extreme heat events are not explicitly modeled, the findings reflect relative performance under representative climatic conditions rather than guaranteed resilience under extreme heatwaves.

With rapid global economic growth and a rise in disposable household income, particularly within a progressively warming planet, the escalating demand for energy to achieve thermal comfort has become a salient concern in the Global South, notably in emerging economies like India. This burgeoning need for cooling solutions has not only underscored the vital role of energy consumption but has also accentuated the imperative of comprehending the ensuing implications for electricity policy and strategic planning, particularly within the ambit of the Global South. This study explored the nuanced landscape of active cooling within an intentional community, Auroville, in southern India, aiming to discern the factors underpinning household preferences and practices in the pursuit of thermal comfort. Employing a mixed-methods approach, this study contributed empirically and methodologically to the interdisciplinary discourse by analysing residential electricity consumption patterns and cooling practices within selected households in the specified community. The study unfolded in three methodological stages: firstly, an analysis of climatic data coupled with an environmental stress index (ESI) assessment; secondly, the monitoring of end-user electricity consumption followed by rigorous data analysis; and lastly, the utilisation of qualitative in-depth interviews and observational techniques. This study’s outcome yielded empirical insights into the unprecedented shifts in the ESI for Auroville since 2014. Furthermore, the study unravelled the intricate complexities inherent in occupant behaviour within residential structures, thereby offering valuable insights into the practices that shape householders’ cooling preferences. This research enriched the understanding of the dynamics of energy consumption in the pursuit of thermal comfort and contributes to the broader discourse on sustainable development and energy policy in the context of climate change.

Of the 33 global megacities, 10 were situated in South Asia. Extreme heat waves have become an annual phenomenon due to climate change in South Asian megacities, causing severe health issues and even deaths. In this study, we evaluated 29 years (1990–2019) of historical data on heat stress in ten selected megacities (existing and prospective)—New Delhi, Dhaka, Mumbai, Kolkata, Ahmedabad, Chennai, Bengaluru, Hyderabad, Chittagong, and Pune—in India and Bangladesh. We used heat index (HI) and environmental stress index (ESI) analyses to evaluate stress and vulnerability. Our results showed New Delhi, Mumbai, Kolkata, Ahmedabad, and Chennai in India; Dhaka and Chittagong in Bangladesh were already experiencing an elevated number of hours of “danger” levels of heat stress, which may lead to heat cramps, exhaustion, stroke, and even death. Furthermore, the frequency of “danger” levels of heat stress and vulnerable levels of ESI has increased significantly since 2011 in the selected megacities, which elevated the heat-related vulnerability among the millions of inhabitants in terms of work hours lost for light, moderate, and heavy work due to heat stress. The vulnerable population in the studied megacities might have to reduce annual work hours by 0.25–860.6 h (light work), 43–1595.9 h (moderate work), and 291–2402 h (heavy work) due to extreme heat in 1990–2019. We also discussed the implication of the work-hour loss on productivity, income, gross domestic product, and sustainable development goal progress because of heat stress and its causes and suggested recommendations to reduce its impact.

Bangladesh—recently graduated to developing nation category from a least developed country with an emerging economy also is one of the severely affected countries by climate change—is heading towards a coal-intensive electricity generation mix contrary to global decarbonisation efforts. It is facing formidable challenges in achieving universal access to affordable, reliable, and sustainable electricity, decarbonising the energy mix by 2030 to achieve the objective of Sustainable Development Goal (SDG) 7, despite a 285% increase of installed capacity between 2008–09 and 2020–21 and aiming at achieving 40 GW and 60 GW by 2030 and 2041 with planned expansions, respectively. This study reviewed Bangladesh’s electricity sector developments—demand, generation, transmission, and distribution (T&D)—to identify progress in policies, drivers, and challenges behind the Greenhouse gas (GHG) emissions-intensive future direction. The rapid population and economic growth and shift towards industry-based economy drove the exponential growth in energy demand, eventually influencing the rapid generation capacity and T&D infrastructure development. However, Bangladesh has targeted transitioning from natural gas to coal dominating fuel mix due to the lower renewable potential, energy, and food security challenges, because of the anticipated substantial future electricity demand for becoming an Upper Middle and a High-income country by 2031 and 2041, respectively. We also recommended nuclear energy, (renewable) electricity import and floating solar plants to decarbonise the current trajectory.