Global GreenTag regards decarbonisation as one of its biggest challenges, stating that the development of a carbon-neutral building (or better still, a carbon-positive build) requires access to climate-conscious materials manufacturers whose aim is to help decarbonise the built environment. 

“The long-term consequences of greenhouse gas emissions concern humanity as a whole,” says Lizette Swanevelder, chief executive officer of Global GreenTag Africa.  

Australian insights for local industry 

The paper contained in this article, co-written by David Baggs, Chief Executive Officer of Global GreenTag International, and Dr Nana Bortsie-Aryee, Program Director of Global GreenTagCertTM Certification and a Life Cycle Assessment (LCA) specialist, offers the South African building industry some new approaches. 

Although written for an Australian context, using LCA could apply anywhere, to install more decarbonised products and materials into projects and deliver greater examples of climate-friendly buildings. 

Getting to net-zero 

The built environment contributes about 25% of the global greenhouse gas emissions. To reach the 2050 goal of net-zero, the industry has to decarbonise an estimated three times faster over the next 30 years versus the previous 30 years. Yet even this level of change will be insufficient to keep the global increase to 1.5°C. 

In Australia, reducing embodied carbon in commercial and residential buildings by 10% between now and 2050 will lead to an estimated elimination of at least 63 megatons of emissions. Recently, the industry has been focussed on embodied carbon emissions associated with materials.  

Reducing upfront carbon emissions 

What is the likelihood of the industry reducing upfront carbon emissions levels to net-zero? Assuming material processing and building operations make up about 95% of these emissions, the industry will need substantial change and innovation. 

Responsible decarbonisation 

The decarbonisation of materials and embodied carbon will require changes to processes and supply-chain decision making. Which begs the question: On what basis are decisions made to drive change in the correct direction without generating unintentional consequences, i.e., increasing other chemical pollutants or water consumption? 

Life Cycle Assessment (LCA) 

The study of LCA can enable both innovation and responsible supply chain decision-making. This tool allows for the estimation of all impacts, including carbon emissions, for building materials beginning with the raw material extraction phase, through manufacturing, packaging and transport, to the product’s fate at the end of its initial “life”. 

The analysis involved in LCA can be used internally by product manufacturers to identify impact hotspots, including carbon emissions, within the supply chain. It can also inform decisions on how best to reduce the carbon emission intensity of these hotspots. 

LCA studies can also assist, where information is available, in choosing specific lower-carbon components, ingredients and processes. All these contribute to what has been previously known as “embodied carbon” and, as indicated, is now described as “upfront carbon” in the Green Building Council of South Africa’s (GBCSA’s) Green Star buildings rating tool.  

LCA inventory data 

LCA generates volumes of complex “inventory” data to develop the final set of indicators, including the total upfront carbon emissions data. Much of this inventory data is highly confidential, provided by third-party suppliers under non-disclosure agreements, and will therefore never be released. The summarised and de-identified data is published in standardised formats, and mandatory minimum content, according to various international standards. 

The publication of these summary LCA reports, or Environmental Product Declarations (EPDs), is to maximise the potential comparability of products from different manufacturers and LCA providers. 

Summary reports (EPDs) 

EPDs are the starting point that allows product manufacturers, architects, specifiers and developers to review and discuss how they can contribute to decarbonising the built environment and meet emissions targets. Based on the data within EPDs, architects, designers, engineers, builders and their project LCA consultants can drive the decarbonisation process by preferred low-carbon products and materials selection.  

Green Building Council of Australia (GBCA) climate-positive pathway for Green Star® buildings  

The minimum expectations of the pathway are: 

  • Six-star buildings will immediately meet the requirements for a 20% upfront carbon emissions reduction, and five-star buildings from January 2023. 
  • From 2030, six-star buildings will be required to reduce upfront emissions by 40%. 
  • By 2050, all certified buildings will be required to reduce upfront emissions by 40%.  

This is no simple task given that Green Star rules exclude the potential for including biogenic carbon – from biologically based materials such as wood, wood-fibre and bamboo – which are frequently included preferentially. They are usually net-carbon sinks, calculated to reduce upfront carbon in structures, and appearing to give preference to existing high-carbon materials such as steel and concrete. 

Arguably, this pushes manufacturers towards low-emission energy sources, or to purchase recognised carbon offsets, notwithstanding that they already have biogenic carbon-sink potential in their products. 

Working with Green Star, an ‘Upfront Carbon Emissions Calculator’ enables a project team to calculate their embodied carbon impacts from key and generic products, and materials used in the building’s construction. It is a simple calculator for those not doing a whole-of-project LCA study and is measured in kgCO2e. 

Life Cycle Impacts 

An alternative approach is the whole-of-project Life Cycle Impacts credit that requires a project to capture LCA data from various sources, including product-specific EPDs, but also less preferred generic or industry-average data-based EPDs. The building, its specified products and materials are compared against a reference building, modelled by the project team using nominated benchmark materials.  

This is a much more complex process, using EPDs from manufacturers to allow design teams to select upfront carbon emissions, preferred products and materials. Typically on larger projects, it is this specific Life Cycle Impacts credit that increases demand for EPDs from manufacturers and suppliers 

Unlocking potential to decarbonise 

A study revealed that embodied carbon will be responsible for over 80% of Australia’s built environment emissions by 2050 if all stakeholders do not take steps. 

In examining the carbon emissions pathway and the growing uptake of Green Star building tools here in Africa there is little doubt that the building industry at large can unlock the potential to decarbonise the built environment by increasing the use of the GBCSA’s Green Star® tools, and encouraging the use of LCA product certifications and EPDs for decision-making across all sectors of the industry. 

Full acknowledgement and thanks go to the information in this editorial. 

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