Guwahati: Researchers at the Indian Institute of Technology (IIT) Guwahati have developed energy-efficient bricks capable of naturally reducing indoor temperatures, offering a potential breakthrough for sustainable construction in hot and humid regions.
The innovation, led by Prof. Pankaj Kalita of the School of Energy Science and Engineering, uses Phase Change Materials (PCMs) embedded within Autoclaved Aerated Concrete (AAC) bricks to regulate heat flow.
The findings have been published in the Journal of Energy Storage and co-authored by Dr. Pushpendra Singh, along with researchers Bitupan Das and Urbashi Bordoloi.
Modern buildings rely heavily on air conditioning systems to maintain comfortable indoor temperatures, particularly during summer months. However, such systems consume large amounts of electricity and contribute to rising carbon emissions. With growing emphasis on climate-responsive architecture, researchers have been exploring alternatives that reduce dependence on energy-intensive cooling systems.
The IIT Guwahati team focused on limiting heat gain through walls and roofs—key entry points for external heat—by modifying conventional bricks.
Their solution involves integrating PCMs, materials that absorb and release heat during phase transitions. Substances such as wax, for instance, absorb heat as they melt and release it as they solidify, helping stabilise indoor temperatures.
Among the materials tested, OM35 emerged as the most suitable PCM. With a melting point of around 35°C, it is particularly effective in climates where temperatures typically range between 28°C and 38°C.
According to Prof. Kalita, the developed biocomposite-filled AAC brick maintains structural stability while offering sufficient mechanical strength under hot and humid conditions, making it viable for construction purposes.
One of the primary challenges with PCMs is leakage during the melting phase. To address this, the researchers combined the PCM with biochar, a carbon-rich material that acts as a supporting matrix. This prevents leakage while also improving thermal conductivity.
AAC bricks are already valued for their lightweight and insulating properties. The addition of the biocomposite PCM further enhances their thermal performance, enabling improved heat management compared to conventional building materials.
Simulations conducted by the research team indicate that the developed bricks can reduce indoor wall temperatures by approximately 3°C. This, in turn, could lead to a 10 to 20 per cent reduction in cooling energy demand, depending on building design and usage patterns.
The estimated cost of the bricks currently ranges between Rs 115 and Rs 130 per unit, with the potential to decrease through mass production. The research team is now exploring avenues for commercialisation, including the possibility of launching a start-up.
The innovation could have significant implications for reducing overall energy consumption and peak electricity demand, particularly in regions where cooling accounts for a large share of power use. It also aligns with global efforts to promote low-carbon construction practices and sustainable urban development.
However, researchers noted that the technology is still at the laboratory stage and requires further validation before it can be deployed at scale.
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