Sustainable building materials

Source-This post on sustainable building materials has been created based on the article “On sustainable building materials” published in “The Hindu” on 26 March 2024.

UPSC Syllabus–GS Paper-3- Environmental Pollution and Degradation, Environmental Impact Assessment.

Context- India housing construction sector is booming, with over 3,00,000 housing units built annually. However, the building sector is a major energy consumer that accounts for over 33% of India’s electricity usage, contributing to environmental degradation and climate change.
Further, The India Cooling Action Plan predicts an eight-fold increase in cooling demand between 2017 and 2037. Thus, it is important to address energy inefficiency in residential buildings due to India’s rising energy and cooling demand.

What are the steps taken by the government to make construction sector energy efficient?

1) The government has taken steps like the Eco-Niwas Samhita (ENS) and the Residential Energy Conservation Building Code to ensure energy efficiency.

2) The ENS introduces the Residential Envelope Transmittance Value (RETV). This is a metric which measures heat transfer through a building’s envelope.

Significance of RETV– Lower RETV values lead to cooler indoor environments and decreased energy usage.
RETV of 15W/m2 or less is recommended for optimal efficiency, improved occupant comfort, and lower utility expenses.

What are the optimal construction materials for energy efficiency of buildings?

There are 4 popular materials such as Autoclaved Aerated Concrete (AAC) blocks, red bricks, fly ash, and monolithic concrete (Mivan).

Read more- Indian Cooling Action Plan

What is RETV evaluation for these construction materials?

1) Autoclaved Aerated Concrete (AAC)– During evaluation, AAC blocks consistently had the lowest RETV across all climatic conditions. They have lower embodied energy compared to monolithic concrete and red bricks. However, they still contribute to emissions and waste.

2) Monolithic Concrete– Monolithic concrete has an embodied energy 75 times greater than AAC for building materials.
Monolithic concrete, despite its quick construction time, poses a significant environmental impact, and sustainability challenges.

Note– Embodied Energy is the energy associated with the manufacturing of a product.

3) Red brick-For estimated construction time for a 100 sq. ft room, red bricks required the longest time. Red bricks exhibit moderate embodied energy, contributing to resource depletion, emissions, and waste.

What should be the way forward?

1) Interdisciplinary Collaborations-There is a need for fostering collaborations   with sustainability experts to develop strategies like building orientation, Window Wall Ratio (WWR), U-value (rate of heat transfer) of walls etc. to ensure energy efficiency.

2) Innovation-There is a need for innovation from building materials manufacturers so that they can develop cost-effective, scalable, durable, fire-resistant solutions.

Question for practice

What is RETV evaluation for construction materials? What steps can be taken to ensure optimal RETV evaluation?