Embodied carbon in construction materials: a framework for quantifying data quality in EPDs

Abstract

Embodied carbon constitutes a significant portion of a building's greenhouse gas (GHG) emissions and is a key challenge for the construction and real estate sectors. Embodied carbon includes construction product manufacturing, building construction, material replacement and end of life. During the specification and procurement stage, designers and contractors have the opportunity to prioritize products with lower carbon footprints. Environmental product declarations (EPDs) are a growing source of environmental data in the construction products market, and are increasingly being used for (1) environmental performance assessment of buildings and (2) product comparison for procurement decisions during the later stages of building design. An obstacle to identifying and purchasing lower embodied carbon products is a lack of data quality and the transparency of EPDs. However, EPDs vary widely in their data quality and specificity, which can lead to inaccurate and misleading comparisons. A new method is presented to account quantitatively for estimates of variation in underlying data specificity in EPDs to enable fairer comparisons between EPDs and to motivate the reporting of actual variability and uncertainty in EPDs. The application of this approach can help purchasers to assess EPDs quantitatively. Practice relevance Life-cycle assessments (LCAs) and LCA data can be used within the construction sector to evaluate buildings and to assist in design, specification and procurement decision-making. A new method is presented to support the assessment of comparability of functionally equivalent materials and products during the specification and procurement stage. Given the known variation and lack of precision within EPDs, this method provides quantitative metrics that correlate to a qualitative interpretation of EPD precision. This method can be used by anyone who is using EPD data to make product comparisons at the specification and procurement stage: • It provides more confidence in choosing low-carbon material or product options when comparing between functionally equivalent options. • It can incentivize product manufacturers and LCA practitioners to improve data quality and transparently report known variation in their EPDs. • It may also motivate manufacturers to reduce GHGs from their products and processes.

Achieving zero carbon emissions in the construction sector: The role of timber in decarbonising building structures

“…Upfront emissions are caused during the materials production and construction phases of the lifecycle before the building or infrastructure begins to be used 57 . This upfront carbon usually comprises the majority of a material's embodied carbon impact, and is considered especially important due to the importance of reducing carbon emissions as quickly as possible 58 . A recent study that analysed the GHG emissions at the time of occurrence showed that the upfront 'carbon spike' from building production, highlighting the need to address and reduce the GHG 'investment' for new buildings 59 .…”

“…Environmental Product Declaration (EPD), also known as a type III label, is a standardised, third-party verified LCA-based label that provides "quantified environmental data using predetermined parameters and, where relevant, additional environmental information" 68 . EPDs are a growing source of environmental data in the building products market, and are increasingly being used for (1) environmental performance assessment of buildings and (2) product comparison for procurement decisions during the later stages of building design 58 . Several studies show that EPDs represent an advantage when used as LCA data source compared to generic data 69 .…”

Environmental Product Declarations of Structural Wood: A Review of Impacts and Potential Pitfalls for Practice

“…They further pointed to the need for more detailed rules for consistency in PCRs and for more transparency in the EPD reports. Other studies of EPDs have emphasized the need for interpretation and uncertainty evaluations of EPDs [39,40] to make them applicable in practice.…”

Quantifying Environmental Burdens of Plasters Based on Natural vs. Flue Gas Desulfurization (FGD) Gypsum

“…The EPD, also known as type III environmental declaration, is meant to deliver transparent, reliable, quantified, and comparable information on products' environmental impact during their life cycle [19,20]. Many different EPD's programs operate by Product Category Rules (PCRs), and EPDs vary in their data quality and specificity, often leading to misleading comparisons [21][22][23][24][25][26]. Unfortunately, the use of data presented in EPD's is still limited.…”