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Impact of Naturally Ventilated Residential Units on Heat Stress (2023)
Authors: Shreeparna Ghosal, Rajan Rawal
Abstract:

In recent years, the adaptive model of thermal comfort has gained traction as a more robust alternative to fixed set-point-driven design, which considers various factors that impact human comfort, such as humidity, air velocity, mean radiant temperature, and ambient temperature. Nonetheless, it is crucial to recognize the limitations of such models and the potential for discomfort and stress. This research employs simulations to systematically evaluate WBGT as a parameter to measure heat stress in residential buildings in Bhubaneshwar, India, comparing ventilation scenarios. The study assesses three building envelope materials: Conventional (RCC and Brick) and Innovative (EPS Core). The ECBC-R[11] standard and a dynamic method derived from regression analysis predicts heat stress, analysing natural ventilation in residential units using the IMAC-R and ISO 7243  benchmark.

Heat stress profoundly affects well-being in hot climates. With the rise of energy-efficient, naturally ventilated buildings, understanding their impact on heat stress is crucial. This is particularly significant in countries like India, grappling with climate change-induced heat waves. The study focusses on the factor of heat stress in adaptive thermal comfort models, emphasizing the need for a more holistic approach to indoor comfort factors. Insights gained can lead to improved strategies for optimal thermal comfort and reduced heat stress risks, vital for occupant health. Indoor WBGT ranged from 16°C to 33°C for various envelopes, averaging 28°C (RCC), 24°C (Brick), and 22°C (EPS). Indoor air velocity of 0.9-1.8 m/s lowered WBGT by 0.15°C or 0.27°C annually. Discomfort hours were ~5,000 (RCC), 3,600 (Brick), and 3,200 (EPS), peaking in May-June at 40°C outdoor DBT. Proper insulation and ventilation are crucial for comfort and heat stress reduction. By considering diverse factors affecting indoor comfort, it offers insights to create safe and comfortable indoor environments, especially in regions prone to heat stress. The findings advocate a balanced approach that combines effective insulation and ventilation strategies for optimal occupant well-being. 

Supported by:

Ministry of New and Renewable Energy Govt. of India, Gujarat Energy Development Agency, U.S. Agency for International Development iNDEXTb (Industrial Extension Bureau) Govt. of Gujarat, Shakti Sustainable Energy Foundation, New Delhi