Buildings are big GHG emitters; here’s how to decarbonise them
According to IPCC, efficient policies in the real estate sector can reduce GHG emissions by up to 90% in developed and up to 80% in developing countries
India might exceed its carbon budget way ahead of the self-adopted 2070 deadline if left to the ‘business as usual’ scenario in the building sector, a report released by a think tank on March 18 said. The study by the Centre for Study of Science, Technology and Policy (CSTEP) advocated the adoption of cleaner fuel and solar energy instead, noting that the sector could reduce emissions by up to 59%. The report ‘Pathways to Steer India’s Buildings Sector Towards a Net-Zero’ said India’s building sector currently accounts for 25% of the country’s greenhouse gas (GHG) emissions, even as most of the stock required by 2030 is yet to be built.
WHAT IS CARBON BUDGET?
The sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC AR6) estimated the remaining global carbon budget (from 2020 onwards) for a 50% chance of limiting global warming to 1.5°C to be 500 gigatonnes of CO2 equivalent. The report said that every 1,000 billion tonnes of CO2 emissions results in an estimated 0.45°C increase in global surface temperature.
The 2015 Paris Agreement decided to limit global warming (human-induced increase in global temperatures) to “well below” 2°C (from the pre-industrial era) and pursue efforts to stay under 1.5°C.
This goal necessitates limiting carbon dioxide emissions to within a defined carbon budget. The remaining carbon budget signifies the amount of CO2 that can still be emitted after the pre-industrial period while keeping the temperature rise from 1.5°C to 2°C.
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The IPCC AR6 has shown that the world warmed by 1.07°C until 2019 from pre-industrial levels, which means almost four-fifths of the global carbon budget is already over. Only a fifth of the total remains to meet the 1.5°C target set in the Paris Agreement.
REPORT FINDINGS
Analysing different scenarios, the report said India’s building sector emissions in the business-as-usual scenario (BAU) will reach 90.85 gigatonnes of carbon dioxide equivalent by 2070, exceeding the country’s entire carbon budget, which is currently estimated at 89 gigatonnes, by 2%.
Under the ‘decent living standards’ (DLS) scenario, which includes housing, cooking, education, and health for all by 2030, the report said, emissions will increase to 97.11 gigatonnes of CO2 equivalent, exceeding the carbon budget by 8%.
Adopting ‘the buildings-led scenario’ (BLS), which means cleaner cooking fuel and rooftop solar power, will reduce annual construction emissions by 16%. In comparison, yearly operational emissions while the buildings are in use could be reduced by 69%.
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Indirect emissions from building materials and electricity consumption could constitute 30% and 50% of the total sectoral emissions.
The integrated scenario (BLS+ILS) would see a 72% reduction in emissions and a 47% reduction in energy demand in 2070, saving 1.83 gigatonnes of CO2 equivalent emissions.
Buildings emit GHGs by using more fossil fuel-based electricity than solar energy, having inefficient designs, requiring artificial lighting even during the daytime, and using air-conditioned cooling rather than minimising heat through architectural features. The use of older fans and ACs that run on chlorofluorocarbons has even higher emissions. Most importantly, buildings emit GHGs by using cement and steel manufactured in factories powered by coal.
The CSTEP report said that the building sector accounts for 37% of energy and process-related CO2 emissions and more than 34% of the global energy demand.
According to IPCC, efficient policies in the building and construction sectors can reduce greenhouse gas (GHG) emissions by up to 90% in developed countries and up to 80% in developing countries, helping lift 2.8 billion people out of energy poverty in developing countries.
NEED FOR BINDING NORMS
A 2022 study by Shakti Sustainable Energy Foundation found the building sector accounts for over 30% of India’s electricity use. The study said as Indian cities grow, the energy demand from buildings would surge, and it must shift from coal to solar and rooftop solar, but that transition is prolonged.
Mitashi Singh, manager of the sustainable buildings and habitat programme at the Centre for Science and Environment (CSE), said, “The building sector has not stopped growing, and we expect to add about two-thirds of the infrastructure that we need for 2030 in the next few years. That is a lot. When we do that, we also expect that by 2050 or so, we will at least triple the energy used in the sector and quadruple the carbon emissions linked to this sector. In the absence of any policy or intervention or any code or stringent scenario where the development is guided in a net zero fashion, we will overshoot it. “
Singh pointed out two types of building codes. The first is the national building code by the Bureau of Indian Standards, which is not mandatory. It is a guiding document that tells you how much concrete to put in when making a slab.
The second is building bylaws, a compulsory code that guides building and construction.
India’s town and country planning organisation, which falls under the Union ministry of housing and urban affairs, formulates the building bylaws that are adopted by states and urban local bodies. The last set of model building bylaws was framed in 2016.
“The problem with these codes is that they do not incorporate low-carbon construction methods,” Singh added.
The Union government’s Bureau of Energy Efficiency developed Eco-Niwas Samitha (ENS) in 2018, an energy-conservation residential building code that promotes energy-efficient design and low-carbon construction materials. The code also aims to raise awareness of energy-efficient building techniques across the industry.
A report by the World Resources Institute published in January 2024 said that 23 out of the 28 states in India have been notified of this code. However, implementation by construction professionals is still lagging and needs to be further enforced by the state governments and urban local bodies.
