Context

India is witnessing an unprecedented construction boom, with over 3,00,000 housing units manufactured annually that poses significant environmental challenges. 

Sustainable Construction Materials: Balancing Economic Growth with Environmental Sustainability

• High Energy User Sector: The building sector, a major energy consumer, accounts for over 33% of India’s electricity usage, contributing to environmental degradation and climate change. 
• Increasing Demand: Also, the India Cooling Action Plan (ICAP) forecasts an eight-fold increase in cooling demand between 2017 and 2037, emphasizing the need for thermal comfort while reducing active cooling demand. 
  • ICAP supports the adoption of climate-friendly alternatives and promotes energy efficiency during the hydrochlorofluorocarbons phase-out. 

Initiatives taken by the Government for Energy-Efficient Construction Sector

• The Eco Niwas Samhita (ENS) and the Residential Energy Conservation Building Code. 
• The ENS introduces the Residential Envelope Transmittance Value (RETV), a metric measuring heat transfer through a building’s envelope. 
  • Lower RETV values lead to cooler indoor environments and decreased energy usage. 
  • For optimal efficiency, improved occupant comfort, and lower utility expenses, an RETV of 15W/m2 or less is recommended. 

Optimal Construction Materials

• Autoclaved Aerated Concrete or AAC Blocks
• Red Bricks
• Fly Ash
• Monolithic Concrete (Mivan)

RETV Evaluation for the Construction Materials

• Autoclaved Aerated Concrete or AAC Blocks: They consistently had the lowest RETV across all climatic conditions, indicating their potential as a thermally efficient material. They have lower embodied energy compared to monolithic concrete and red bricks, while still contributing to emissions and waste.
  • AAC blocks offer a better balance between embodied energy and construction time than red bricks and monolithic concrete.
    • Embodied energy is the energy associated with the manufacturing of a product. 
• Monolithic Concrete (Mivan): Despite its quick construction time, it presents the highest embodied energy (an embodied energy 75 times greater than AAC blocks), significant environmental impact, and sustainability challenges. 
  • Despite concerns about sustainability, it was favored by building developers for its speed, strength, quality, and scalability.
  • Over 60% of buildings under design and construction phases opt for it, especially in high-rise buildings and skyscrapers.
    • It offered faster construction of buildings compared to traditional masonry work, particularly for taller structures.
• Red Bricks: For estimated construction time for a 100 sq. ft room, red bricks required the longest time. 
  • They exhibit moderate embodied energy, contributing to resource depletion, emissions, and waste. 

Way Forward

• Interdisciplinary Collaborations: Collaborations with sustainability experts is a need to unlock the potential for a sustainable built environment.
  • Example: For integrated design and optimise strategies like building orientation, Window Wall Ratio (WWR), U-value (rate of heat transfer) of walls, roofs and window assemblies, glazing performance, active cooling systems, etc. 
• Innovation: Sustainable construction requires innovation from building materials manufacturers to develop cost-effective, scalable, durable, fire-resistant solutions with superior thermal performance and climate resilience.
• Knowledge and Awareness: There is a need to have more widespread knowledge about climate-appropriate design and architecture.

Conclusion

The journey toward sustainable construction is challenging but essential for a greener future. The goal can be achieved by re-imagining construction design and practices, manufacturing innovative walling materials, and fostering a culture of sustainability, resilient and energy-efficient structures that align with environmental goals and significantly improve the quality of life for the masses.