Why is addressing energy inefficiency in residential buildings important?
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.
Initiatives like the Eco-Niwas Samhita (ENS) and the Residential Energy Conservation Building Code are steps in the right direction.
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, it’s recommended to maintain an RETV of 15W/m2 or less.
However, current construction trends favour fast-paced, energy-intensive techniques with active cooling strategies, leading to compromises in thermal comfort.
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.
What is Residential Envelope Transmittance Value?
The RETV evaluation for these buildings revealed that AAC blocks consistently had the lowest RETV across all climatic conditions, indicating their potential as a thermally efficient material.
Based on literature review, a comparison of building materials for a 100 sq. ft wall area displayed substantial differences in embodied energy.
It is with monolithic concrete having an embodied energy 75 times greater than AAC.
When considering the estimated construction time for a 100 sq. ft room, red bricks required the longest time, while Mivan construction required the least.
Mivan technology offered faster construction of buildings compared to traditional masonry work, particularly for taller structures.
Sustainability concerns are prominent across all materials.
Red bricks exhibit moderate embodied energy, contributing to resource depletion, emissions, and waste.
While AAC blocks have lower embodied energy, they still contribute to emissions and waste.
Monolithic concrete, despite its quick construction time, presents the highest embodied energy, significant environmental impact, and sustainability challenges.
Hence, AAC blocks offer a better balance between embodied energy and construction time than red bricks and monolithic concrete.
Why are Autoclaved Aerated Concrete blocks the optimal building material with respect to embodied energy and construction time?
Our analysis across four warmer climate cities in India highlighted the popularity of materials like AAC blocks, red bricks, fly ash, and monolithic concrete (Mivan).
Despite concerns about sustainability, monolithic concrete construction was favoured by building developers for its speed, strength, quality, and scalability, with over 60% of buildings under design and construction phases opting for it, especially in high-rise buildings and skyscrapers.
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