Context:
India is experiencing an unparalleled surge in construction, with more than 300,000 housing units being built each year. While this growth presents economic prospects and enhances living conditions, it also presents significant environmental hurdles.
Relevance:
GS3-Environmental Pollution & Degradation
Mains Question:
Why is addressing energy inefficiency in residential buildings important? What are some of the optimal building materials with respect to embodied energy and construction time? How can India achieve energy efficiency in the construction industry? (15 Marks, 250 Words).
India’s Construction Sector:
- The construction sector, a substantial energy user, consumes over 33% of India’s electricity, leading to environmental degradation and contributing to climate change.
- The India Cooling Action Plan predicts an eight-fold rise in cooling demand from 2017 to 2037, underscoring the importance of achieving thermal comfort while minimizing the need for active cooling methods.
The Construction Industry and Energy Efficiency:
- Addressing energy inefficiency in residential buildings is essential, particularly considering India’s escalating energy and cooling demands due to economic expansion, urbanization, urban heat islands, and climate change.
- Initiatives like the Eco-Niwas Samhita (ENS) and the Residential Energy Conservation Building Code represent positive strides in this direction.
- The ENS introduces the concept of the Residential Envelope Transmittance Value (RETV), a metric gauging heat transfer through a building’s envelope.
- Residential Envelope Heat Transmittance (RETV) is defined as the rate of net heat gain (during the cooling period) through the building envelope of residential units (excluding the roof), divided by the area of the building envelope (excluding the roof) of residential units. Its measurement unit is watts per square meter (W/m²).
- Lower RETV values result in cooler indoor environments and reduced energy consumption.
- For optimal efficiency, enhanced occupant comfort, and decreased utility costs, it is recommended to maintain an RETV of 15W/m2 or less.
Which materials are most suitable?
- An examination of four warmer climate cities in India highlighted the prevalence of materials such as Autoclaved Aerated Concrete (AAC) blocks, red bricks, fly ash, and monolithic concrete (Mivan).
- Despite sustainability concerns, monolithic concrete construction was preferred by developers due to its speed, durability, quality, and scalability.
- Over 60% of buildings in the design and construction phases opted for monolithic concrete, especially in high-rise buildings and skyscrapers.
- The evaluation of Residential Envelope Transmittance Value (RETV) for these buildings revealed that AAC blocks consistently exhibited the lowest RETV across all climatic conditions, suggesting their potential as thermally efficient materials.
- A review of literature comparing building materials for a 100 sq. ft wall area showed significant differences in embodied energy (the energy consumed during product manufacturing), with monolithic concrete having an embodied energy 75 times higher than AAC.
- When considering the estimated construction time for a 100 sq. ft room, red bricks required the longest duration, while Mivan construction required the least.
- Mivan technology facilitated faster building construction compared to traditional masonry work, particularly for taller structures.
- Sustainability concerns are a primary consideration across all materials. Red bricks, while displaying moderate embodied energy, contribute to resource depletion, emissions, and waste. Although AAC blocks have lower embodied energy, they still contribute to emissions and waste.
- Monolithic concrete, despite its rapid construction time, presents the highest embodied energy, significant environmental impact, and sustainability challenges.
- Consequently, AAC blocks offer a better balance between embodied energy and construction time compared to red bricks and monolithic concrete.
Way Forward:
- India possesses significant untapped potential for innovative building materials. Collaborations across disciplines with sustainability experts to explore integrated design and optimize strategies such as building orientation, Window Wall Ratio (WWR), U-value (rate of heat transfer) of walls, roofs, and window assemblies, glazing performance, and active cooling systems can unlock the potential for a sustainable built environment.
- The construction industry’s preference for Mivan as a primary building material raises sustainability concerns, including high embodied carbon and thermal discomfort.
- Achieving sustainable construction necessitates innovation from building materials manufacturers to create cost-effective, scalable, durable, fire-resistant solutions with superior thermal performance and climate resilience.
- However, prevailing construction practices often prioritize rapid, energy-intensive methods coupled with active cooling strategies, leading to compromises in thermal comfort. There is a pressing need for broader dissemination of knowledge about climate-appropriate design and architecture.
- Moreover, perceptions regarding high initial costs must change to encourage the design and construction of climate-responsive buildings.
Conclusion:
The path to sustainable construction is demanding but vital for a more environmentally friendly future. By rethinking construction design and practices, developing innovative walling materials, and promoting a culture of sustainability, we can construct resilient and energy-efficient structures that align with environmental objectives and significantly enhance the quality of life for the population.
