Context

India is witnessing an unprecedented construction boom, this growth brings economic opportunities and improved living standards but also poses significant environmental challenges. Therefore, addressing energy inefficiency in residential buildings is crucial, given India’s rising energy and cooling demand due to economic growth, urbanisation, heat islands, and climate change. 

1: Dimension-Unprecedented construction boom

• Growth in building sector: The building sector is a major energy consumer, it accounts for over 33% of India’s electricity usage, contributing to environmental degradation and climate change. Over 3,00,000 housing units are getting erected annually.
• Increasing cooling demand: The India Cooling Action Plan forecasts an eight-fold increase in cooling demand between 2017 and 2037, emphasising the need for thermal comfort while reducing active cooling demand.
• Challenges in construction sector: Natural sand is fast becoming a scarce resource. Carbon dioxide emissions, especially from manufacturing cement or fired clay bricks, are increasing every year. The amount of construction and demolition (C&D) waste is on the rise—about 150 million tons are generated annually in India and the recycling rate is only about1%.

2: Dimension-Initiatives to make construction sector energy efficient

Initiatives like the Eco-Niwas Samhita (ENS) and the Residential Energy Conservation Building Code are steps in the right direction.

• Eco-Niwas Samhita (ENS) is India’s building energy code for residential buildings. It was launched by the Bureau of Energy Efficiency. 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.
• Energy Conservation Building Code (ECBC)sets minimum energy standards for new commercial buildings having a connected load of 100 kW or contract demand of 120 kVA or more.

3: Dimension-Challenges and Required Measures:

• Issue (compromise in techniques): Current construction trends favour fast-paced, energy-intensive techniques with active cooling strategies, leading to compromises in thermal comfort.
  • Solution (awareness): There needs to be more widespread knowledge about climate-appropriate design and architecture, with perceptions of high first costs as a barrier to the design and construction of climate-responsive buildings needing to change.
• Issue (Sustainability concerns across materials): Autoclaved Aerated Concrete (AAC) blocks, red bricks, fly ash, and monolithic concrete (Mivan) are most popular material.  Red bricks exhibit moderate embodied energy, contributing to resource depletion, emissions, and waste.  Monolithic concrete have an embodied energy 75 times greater than AAC. Monolithic concrete, despite its quick construction time, presents the highest embodied energy, significant environmental impact, and sustainability challenges.
  • Solution (sustainable material): AAC blocks consistently had the lowest RETV across all climatic conditions, indicating their potential as a thermally efficient material. Hence, AAC blocks offer a better balance between embodied energy and construction time than red bricks and monolithic concrete.
• Issue (Untapped potential): India has significant untapped potential for innovative building materials.
  • Solution (re-imagining construction design and practices): Building orientation, Window Wall Ratio (WWR), U-value (rate of heat transfer) of walls, roofs and window assemblies, glazing performance, active cooling systems, etc., can unlock the potential for a sustainable built environment.