Researchers at the Indian Institute of Technology Madras (IIT-Madras) have predicted that the rapid urbanisation of Chennai could result in the cumulative emission of 231.9 million tonnes of carbon dioxide (CO2) from the construction and operation of buildings alone by 2040. They also suggested that switching to renewable energy sources for building operations could be an effective way to reduce these emissions.

As per their press release, the study was conducted by a team of researchers from the Centre for Technologies for Low Carbon and Lean Construction at IIT Madras and the Indo-German Centre for Sustainability (IGCS) at IIT Madras. The team was composed of Professor Ashwin Mahalingam from the Department of Civil Engineering at IIT Madras and Pokhraj Nayak, a former student at IIT Madras.

To address the issue of CO2 emissions, the researchers conducted a quantitative study in three phases:
Phase 1: The team used geo-spatial modeling techniques to simulate how Chennai would look in 2040.
Phase 2: Researchers used Life Cycle Analysis (LCA) techniques to understand the extent of carbon emissions that Chennai would accrue due to urbanisation.
Phase 3: The team developed several scenarios where alternative building materials and energy sources are used in Chennai's development to evaluate technologies that could lead to the largest reduction in emissions.

Professor Ashwin Mahalingam of the Department of Civil Engineering at IIT Madras provided more details about the study, stating, “In order to achieve our emissions targets, we need to benchmark what our ‘business as usual’ emissions are likely to be in future and work backwards. This study represents a step in trying to quantitatively address this problem.”

Measures suggested by researchers include:
1. Replacing traditional cement with low-carbon cement
2. Reusing demolition waste for future construction
3. Switching to renewable resources to meet the energy requirements of operating buildings.

The findings of the study showed that the single largest factor in reducing emissions was the change in energy sources. Using clean energy sources to supply 50% of a building's operational energy needs could result in a corresponding reduction in cumulative CO2 emissions of up to 115 million tonnes between 2019 and 2040. The researchers found that replacing traditional cement with low-carbon cement had a lower impact on reducing emissions.