Policies and People | The net-zero race: Why embodied carbon matters

Tackle the carbon footprint of construction materials and the supply chain that feeds India's rapidly growing building sector

Last week, the Andhra Pradesh government announced its plans to provide energy-efficient power infrastructure to houses built under its affordable housing programme. This decision is climate-positive because decarbonising the building sector is crucial for India to meet its climate pledges.

The building sector is critical because it is responsible for 30% of the electricity consumed in the country and is second only to the industrial sector when it comes to GHG emissions. (HT File/Representative Image)

The building sector is critical because it is responsible for 30% of the electricity consumed in the country and is second only to the industrial sector when it comes to GHG emissions. The urbanisation rate in India is expected to rise to 40% by 2030–31 and this massive urban transition underpins rapid consumption of energy‐intensive materials such as steel and cement. The manufacturing of building materials is both a resource-intensive and an energy-intensive process. India is the second-largest producer of bricks, steel, and cement in the world.

“By 2030, India will have added nearly one billion square meters of new commercial floor space — more than the land area of New York City and Washington D.C combined,” says Sameer Kwatra, acting director, India, International Program, NRDC. “Building smart from the start is a real opportunity to reduce emissions, save energy and enhance prosperity. The good news is that India is committed to energy-efficient buildings, which are central to India’s Nationally Determined Contributions under the Paris Climate Agreement”.

The green pathway

Carbon emissions of buildings are of two kinds: One is operational carbon (produced from the use of energy to run or operate equipment inside buildings or fuel used in transport or for delivering municipal and services), and the second is embodied carbon, which is associated with procurement, manufacturing, construction, and the use and disposal of building materials over the life cycle of a building.

To reduce operational carbon, it is important to focus on three critical aspects: The building envelope (the structural barrier between the interior and exterior of a building such as roofs, walls, doors, and windows), which are responsible for maintaining cooling and heating within the building, reducing the energy consumption; expanding the usage of energy-efficient appliances and using renewable energy.

The Indian government has taken several initiatives to design buildings that reduce the energy consumption of residents. These include the National Building Code 2016; the Energy Conservation Building Codes 2017 for commercial buildings, and the Eco Niwas Samhita 2018 for residential buildings.

Lower energy consumption, which translates into lower bills, is not the only benefit residents can accrue from the buildings that follow these green codes. Energy-efficient buildings are also more comfortable to live in and improve the wellness and work efficiency of those who live in them.

The thermal comfort of buildings is becoming increasingly important because of the global temperature rise. India is already one of the countries to have experienced the highest loss in labour due to global warming. According to a 2021 study by Duke University researchers, the projected economic losses associated with this lost productivity could reach up to $1.6 trillion ( ₹1.6 lakh crore) annually if warming exceeds an additional 2 degrees Celsius relative to the present.

Embodied carbon: A blind spot

For years now, the building industry has focused its climate efforts on operational-energy consumption from lighting, heating, cooling, hot water, and other plug loads.

However, there is another, less obvious source of GHG emissions associated with buildings: Embodied carbon. “It’s already in the atmosphere, quietly warming our planet, by the time materials reach the project site. And for new buildings, its climate impacts are nearly even with those of operational energy, explains a Mckinsey report, Data to the rescue: Embodied carbon in buildings and the urgency of now.

“There is not much discussion on embodied carbon in India,” says S Maithel, head, Indo-Swiss Building Energy Efficiency Project. “While operational carbon emissions can be reduced over time by decarbonising the electricity grid and with energy-efficient retrofits, decarbonising the entire supply chain can be a tricky affair.” But not tackling this aspect will mean using carbon-intensive materials and unsustainable construction practices, which could irreversibly lock in high energy use and inefficiencies for decades to come.

There are four main options to tackle embodied carbon: Reuse construction material to reduce carbon-density in their production; improve the structural design and reduce wastages so that you require less of these materials; employ new construction techniques; replace the existing materials with greener options such as low-carbon cement.

Unfortunately, embodied carbon is more difficult to measure and track than operational carbon, which is relatively simple to extrapolate from occupants’ energy bills. In addition, determining the embodied carbon of any building material is impossible to ascertain from the finished product alone and requires self-assessment and process transparency on the part of the manufacturer, adds the Mckinsey report.

A zero-carbon building

“A real zero-carbon building is the one that is built, operated and inhabited in a carbon-neutral manner,” explains Kwatra. There can be various ways of moving towards that goal: One, state-of-the-art certification for green buildings; and benchmarking and disclosure (In New York, many commercial and residential buildings disclose their energy consumption). “In the US, there are also material directories and many banks have preferential mortgage terms for those opting low-energy buildings,” adds Kwatra.

Energy experts say it is crucial for India to have a national-level roadmap to have a truly zero-carbon building stock.

“Energy efficiency in buildings, which India is pursuing, is a critical but low-hanging fruit. The country must aim to clean the full sector …. The hydrogen mission that the government announced recently is a good step forward and can make cement and steel production less carbon-intensive,” adds Kwatra.

Decarbonising the built environment is profitable financially and environmentally for the climate crisis-hit country and its people. And if done strategically, India can show other energy‐hungry economies a pathway where economic expansion is possible with emissions reduction, and, in the process, burnish the “climate leader” tag.

The views expressed are personal