IIT Guwahati develops cooling bricks to cut indoor heat, reduce AC use and energy consumption

Researchers at Indian Institute of Technology Guwahati have come up with a new type of brick that can help keep buildings naturally cool, potentially cutting down the need for air conditioning.

The idea comes at a time when rising temperatures, especially in hot and humid regions, are pushing up the demand for cooling. While air conditioners do the job, they also consume a lot of electricity and contribute to carbon emissions, making sustainable alternatives more important than ever.

With this in mind, the team worked on improving how buildings handle heat. Since a large amount of heat enters through walls and roofs, they redesigned traditional bricks to reduce this heat gain and improve indoor comfort.

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Smart bricks use heat-storing materials to regulate temperature

IIT Guwahati said in the statement, “as a significant amount of heat enters the infrastructure through its roof and walls, researchers at IIT Guwahati focused on addressing this challenge by redesigning conventional bricks to minimise heat gain. For the same, Prof. Pankaj Kalita, along with his research team, applied phase change materials (PCMs), a type of material that can absorb and release heat during phase transitions.”

“Among the various PCMs tested, the research team found OM35 to be the most suitable for the research. This material melts at around 35 degrees celsius, making it particularly suitable for hot, humid regions where temperatures range from 28 to 38 degrees celsius,” the statement reads further.

Biochar addition helps improve performance and durability

A common issue with PCMs is that they can leak when they melt. To solve this, the team combined the material with biochar, which acts as a support structure and keeps the PCM in place while also improving heat transfer. The result is a lightweight AAC brick with better insulation properties than conventional ones.

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Pankaj Kalita said, “The developed biocomposite-filled Autoclaved Aerated Concrete (AAC) brick is highly stable in shape and offers adequate mechanical strength in hot and humid conditions, making it suitable for infrastructure development.”

“PCM-embedded bricks are capable of better thermal management in terms of temperature reduction, as they can absorb and store heat during the day and release it gradually when the temperature drops, helping maintain more stable indoor conditions compared to conventional bricks,” he further added.

Study shows potential for cooler interiors and lower energy use

Simulations carried out by the researchers showed that these bricks could lower indoor wall temperatures by about 3°C. This reduction could lead to a 10–20% drop in cooling energy needs, depending on the building’s design and usage.

The cost of the bricks is currently estimated at around Rs 115 to Rs 130, and it could go down further if produced on a larger scale. The institute has noted that the technology is still at an early, laboratory stage and will need further testing before it can be widely used.