Published in Shashwat Volume 7 | Issue 8 – December 2021

India emitted more than 2300 Mt of CO₂ in 2019 and our rate of emissions per capita continues to grow despite a pandemic. (IEA 2020) USA and China have avowed net zero carbon emissions by 2050 and 2060. As the third-largest emitter of negative carbon dioxide, India’s plans need to now be under the spotlight. It is commonly known that building operations account for almost 30% percent of global carbon emissions. It is a lesser known fact that another 10 percent is generated from construction-related industries. (UNEP 2020)

A net-zero status is popularly understood as the gold standard in building energy efficiency. In typical situations, a building achieves this status based on an annual balance sheet of electricity. This balance sheet pressents an environmental evaluation for the building annually in terms of the energy performance index (EPI). The key performance indicator is the annual consumption (EPI) with respect to the onsite generation (net-EPI). It is typically measured in kilowatt-hours (kWh) and expressed as a function of the building area (kWh/m²-yr). The common use of this metric is based on the idea that annual savings in electricity translate to savings in greenhouse emissions. Recent research has suggested that may not be the case. (Bordass 2020)

A net-zero status is achieved through provision of elements like insulation, high performance glazing, on-site photovoltaics etc. The provision of these systems increases in embodied emissions of the building. (Adams, Burrows, and Richardson 2019; Graham 2019; Schmidt, Crawford, and Warren-myers 2020). The annual performance evaluations do not consider the embodied carbon released before the use of the building. With these additional provisions, the embodied emissions of a net-zero building can be higher than those of a typical building. The annual savings may or may not be able to compensate for these additional emissions, even across the lifespan of the building. For the building industry, a positive net-EPI is not good enough to ensure a significant reduction in emissions anymore. It is now necessary to be able to quantify the total impact of a building on the environment across its lifecycle.

The total impact can be quantified through a life cycle analysis (LCA). When typically conducted for economic costs, an LCCA (life cycle cost analysis) not only considers the annual net sum but also looks at initial investments, inflation, depreciation, and residual costs. Similarly, a life cycle carbon analysis needs to include upfront carbon, annual emission, and end-of-life processes. An LCA for a building requires the use of a metric that applies to all phases of a building’s lifespan. This metric needs to account for GHG emissions[i], typically measured in terms of equivalent carbon dioxide (CO₂e). The metric must quantify the emissions from various greenhouse gases based on their global warming potential (GWP). Once the impact is quantified in terms of CO2 equivalent, it can be normalised for time, area, occupants and cost. This normalized value can be used for comparative studies or benchmarking. (Parkin, Herrera, and Coley 2020; Ürge-Vorsatz et al. 2020)

Embodied carbon is projected to account for 50% of the total carbon footprint of new construction until 2050. (Adams, Burrows, and Richardson 2019) Data on embodied carbon can be sourced from lifecycle databases and EPDs based on its applicability to the project’s geography and time. Contextualising data for each project is necessary to come close to the true impact. The share of these emissions in the total life of a building can vary so much that it is not feasible to draw a simple, broadly valid conclusion. The variations in these shares are primarily due to differences in construction materials and technologies.

The handling processes at the end of a building’s lifespan have multiple options as well. The building may be demolished as an entity or consciously dismantled for reuse or recycling. While metals, wood, glass, and plastics may be extracted for reuse and recycling, debris consisting of concrete, bricks, and tiles are typically landfilled. Only a handful of cities in India, like Ahmedabad, have a construction and demolition (C&D) waste recycling facility. The emissions generated due to the use of the facility are rarely included in the environmental impact of the building. However, a cradle-to-cradle analysis necessitates the inclusion of these emissions.

The recent LCA studies in India have dealt with the handloom industry, waste management options, rooftop solar PV systems etc. LCA studies for buildings have been sparse and mostly based on foreign data sources. This is because LCA is both, data-intensive and data sensitive. A methodology for carbon quantification is in place. It is only a matter of finding and using the right datasets. The quantification of carbon leads to the possibility of compensation through carbon offsets.

While offsetting carbon is environmentally crucial, it is important to understand the economic cost it comes at. This is because the cost and benefits of an absolute zero carbon building accrue to different stakeholders during different phases of the building’s lifespan. Many of the financial benefits do not go to developers and constructors, but to occupants, creating a split incentive. Consequently, a high upfront cost is one of the biggest roadblocks for policymakers trying to increase performance requirements while maintaining the viability of the policy. (Graham 2019)

It must be noted that the calculation of the required offset, with no regard to the costs it comes at would be a study in isolation. This incremental cost for carbon offsetting also needs to be put in perspective to the actual cost of the building. For instance, a study conducted by the UK Green Building Council in early 2020 explores the replacement of material to compensate for embodied and operational carbon. The cost analysis reports that incremental cost for an office building was only 6%. These costs were reported to be relatively marginal and expected to be recouped through associated increases in rental and capital value. (UK GBC 2020)

Life cycle analysis and carbon quantification can simplify the road to net-zero carbon. Absolute zero carbon should be the ideal target considering our rate of emissions. With current building technologies, achieving that is not possible. In our current situation, net-zero carbon needs to be the intermediary target. The target will also open up explorations about circularity in design and alternative materials.

[i] GHG emissions in buildings are typically indirect, occurring due to use of electricity in the building. Absolute emissions numbers, therefore, largely depend on emission factors considered during calculation. (Lucon et al. 2014) There is a need to include gases other than CO2 because some construction products and HVAC equipment emit substantial amounts of GHGs such as methane, nitrous oxides and HFCs.

References

• Adams, Matthew, Victoria Burrows, and Stephen Richardson. 2019. “Bringing Embodied Carbon Upfront: Coordinated Action for the Building and Construction Sector to Tackle Embodied Carbon.” Bringing Embodied Carbon Upfront, 35. https://www.worldgbc.org/sites/default/files/WorldGBC_Bringing_Embodied_Carbon_Upfront.pdf.
• Bordass, Bill. 2020. “Metrics for Energy Performance in Operation : The Fallacy of Single Indicators.” Buildings and Cities 1 (1): 260–76. https://doi.org/https://doi.org/10.5334/bc.35.
• Graham, Peter. 2019. “Adopting Decarbonization Policies in the Buildings & Construction Sector: Costs and Benefits.” www.globalabc.org.
• IEA. 2020. “Data & Statistics – IEA.” 2020. https://www.iea.org/data-and-statistics?country=INDIA&fuel=CO2 emissions&indicator=FECI.
• Lucon, Oswaldo, Diana Ürge-Vorsatz, Azni Zain Ahmed, Hashem Akbari, Paolo Bertoldi, Luisa F. Cabeza, Nicholas Eyre, et al. 2014. “Buildings.” In Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, edited by Marilyn Brown and Tamás Pálvölgyi. Cambridge: Cambridge University Press, Cambridge.
• Parkin, Anna, Manuel Herrera, and David A. Coley. 2020. “Net-Zero Buildings: When Carbon and Energy Metrics Diverge.” Buildings and Cities 1 (1): 86–99. https://doi.org/10.5334/bc.27.
• Schmidt, Monique, Robert H Crawford, and Georgia Warren-myers. 2020. “Integrating Life-Cycle GHG Emissions into a Building ’ s Economic Evaluation.” Buildings and Cities 1: 361–78.
• UK GBC. 2020. “Building the Case for Net Zero: A Feasibility Study into the Design, Delivery and Cost of New Net Zero Carbon Buildings,” no. September. https://www.ukgbc.org/wp-content/uploads/2020/09/Building-the-Case-for-Net-Zero_UKGBC.pdf.
• UNEP. 2020. “2020 Global Status Report for Buildings and Construction: Towards a Zero‑emission, Efficient and Resilient Buildings and Construction Sector.” Renewables Global Status Report. http://www.ren21.net/resources/publications/.
• Ürge-Vorsatz, Diana, Radhika Khosla, Rob Bernhardt, Yi Chieh Chan, David Vérez, Shan Hu, and Luisa F. Cabeza. 2020. “Advances toward a Global Net Zero Building Sector.” Annual Review of Environment and Resources 45: (in print).