New Delhi: Researchers from the Indian Institute of Technology (IIT), Guwahati have developed energy-efficient bricks that naturally reduce indoor air
temperatures by around 3°C, which is sufficient to lower cooling energy demand between 10 and 20 per cent. The biocomposite-filled Autoclaved Aerated Concrete (AAC) bricks use Phase Change Materials (PCMs) integrated with biochar, offering a sustainable alternative to energy-intensive air conditioning in hot and humid climates. The innovation has been published in the Journal of Energy storage. Conventional buildings rely heavily on air conditioning for cooling in the harsh summer months, which results in high electricity consumption as well as carbon emissions.
Heat primarily enters the house through the roofs and walls. The IIT Guwahati team addressed this by embedding PCMs into lightweight AAC bricks. PCMs absorb excess heat during the day as they melt, and release it at night when the temperatures drop, stabilising indoor conditions without mechanical cooling. The researchers tested a number of PCM formulations, and determined that one dubbed OM35 proved to be the most effective, melting at around 35°C, which is suitable for regions where the temperatures range between 28 and 38°C. The introduction of biochar prevents the bricks from leaking when they melt, a common problem when using PCMs.
More research is needed before commercialisation
The carbon-rich biochar matrix holds the molten PCM and prevents seepage. The biochar also improves thermal conductivity, while stably maintaining the shape of the brick and the mechanical strength even in hot, humid conditions. Computer simulations were used to optimise the PCM configuration within the bricks, and confirmed superior thermal management properties compared to conventional bricks. The bricks cost between Rs 115 and 130 per unit, which prices expected to fall further with mass production. The research supports climate-responsive architecture, and reduces electricity demand. The researchers plan to advance the technology towards commercialisation, and are considering founding a startup.
