This Kingspan sponsored CPD explains how EPDs are carried out, the advantages they offer in a digitalised industry, and how they are supporting the development of voluntary sustainable building standards such as BREEAM and LEED
When the latest version of BREEAM New Construction was published in 2018, one of the most notable changes was that product BRE Green Guide Ratings were no longer used within the materials section of the assessment. This change represented the first step in the BRE’s commitment to phase out the Green Guide to Specification by the end of 2021 in favour of an approach based on whole building lifecycle assessments (building LCAs) informed through environmental product declarations (EPDs).
Building LCAs allow the environmental impacts of a building to be more accurately considered at different stages in their lifespan, helping specifiers make informed decisions when selecting products. EPDs play a vital role in this process, providing detailed, independently verified information about the various environmental impacts a product may have across part, or all, of its lifespan. In this CPD, we take a look at how EPDs are carried out and the advantages they offer as construction becomes increasingly digitalised. The feature will also look at why recent changes to these approaches now place greater emphasis on circularity and how they are supporting the development of voluntary sustainable building standards (such as BREEAM and LEED).
Why are EPDs becoming more important in construction?
The Green Guide to Specification has been used for more than 20 years in the UK and was designed as a tool to reduce the results from a product lifecycle assessment (LCA) down to a single rating from A+ to F. As well as allowing specifiers to compare products easily or to confirm the overall rating of a construction, this was also intended to drive competition and innovation within the marketplace, ultimately pushing manufacturers to further reduce environmental impacts related to their practices and products.
In contrast, EPD certificates are sometimes criticised for being too complex and inaccessible, often comprising dozens of pages along with in-depth tables detailing different environmental impacts. This makes it very difficult to compare the environmental impact of different products based on their certificate alone. So, why are these documents becoming more relevant?
The simple answer is that as modelling tools and approaches such as building information modelling (BIM) have developed, it has become possible to input, store and process large amounts of detailed information about the various products that make up a building and to put these to practical use. At the same time, the process of generating an EPD has also become standardised via the creation of harmonised standards such as EN 15804.
As a result, a significant number of products are now certified under readily available EPDs that provide comparable, independently verified information about their environmental impact. When processed as part of a building LCA, this allows project teams to gain a better understanding of the environmental impacts the completed building will have and how changes to the specification may impact this.
How are EPDs calculated?
The process of generating an EPD for a particular product is separated into four stages:
a) Product category rules
In order for EPDs to provide useful information as part of building LCAs, clear rules and procedures need to be established to ensure that all products are judged on an equal footing. This is achieved through product category rules (PCRs), which set the rules, requirements and guidelines for assessing products that have a similar function (for example, insulation) through an EPD. The PCR lays out criteria covering various aspects of the EPD and LCA including:
- Clearly defining the products that can be assessed through the EPD
- Setting the scope for the LCA (what environmental impacts will be assessed, what are the boundaries to the assessment)
- Identifying the measurements and data quality requirements
- Setting out what content will be published in the EPD and how long the certificate will be considered valid.
The PCR also describes which stages of a product’s lifecycle should be covered in the EPD. Options generally include:
- Cradle-to-gate: from raw material extraction to when the product leaves the manufacturing site
- Cradle-to-gate with options: from raw material extraction to when the product leaves the manufacturing site and other assessment areas most commonly related to end-of-life routes
- Cradle-to-grave: from raw material production through to waste management routes
- Cradle-to-cradle: from raw material production through to recycled uses.
In the UK, the EPDs for all construction products are based on the European standard EN 15804. This is described as a “core PCR”, designed to ensure that the environmental declarations for construction products are consistent to allow for simple and accurate comparisons between products.
b) Lifecycle inventory
The lifecycle inventory (LCI) stage is when data is collected about the product. It is usually the most time-consuming part of the LCA, requiring an assessor to gather data from the various parties within the supply chain. Once this data is gathered, the assessor uses the PCRs to develop a flow model measuring all of the inputs into the system (such as water, raw materials and energy types) and outputs into the environment.
An example of a simple flow model for the production stage of an insulation board is shown in the diagram below.
Given the complexity of modern supply chains, these inventories and flow diagrams can become very large. For example, the process of getting raw materials to the manufacturing site may include various steps such as extraction, transportation and process, each with their own inputs and environmental impacts. This is why boundaries for the scope of the LCA are clearly set within the PCR.
c) Lifecycle impact assessment
The assessor then needs to make sense of the data collected during the inventory. This involves characterising and categorising the product’s environmental impacts and evaluating the significance of each. For example, the LCI will show how much of a particular energy source (for example, electricity from a combined cycle gas turbine power plant) was used during production. During the lifecycle impact assessment, this data is used to calculate the global warming potential of generating this energy.
There are a wide variety of environmental indicators covering all known aspects of pollution and resource depletion. Examples can range from localised particulate matter to increased soil and water acidification. During the assessment, these impacts are typically first broken down into large groups, which can include:
- Environmental impacts
- Human health
- Resource use
- Waste to disposal.
Each of these impact groups are then separated out further into the individual environmental impact indicators for specific environmental issues. For example, EN 15804+A1 includes seven core indicators:
- Global warming potential
- Eutrophication potential
- Acidification potential
- Fossil fuel depletion rate
- Ozone depletion
- Abiotic resource depletion
- Water use deprivation.
The results of this analysis can then be formatted for the EPD certificate. Within EPDs completed under EN 15804, the impacts are broken down into modules, which cover different stages in a product’s lifespan. These modules are:
- A1-3 (raw material extraction and production stage)
- A4-5 (construction process stage)
- B1-7 (use stage)
- C1-4 (end of life/disposal routes)
- D (reuse, recycling).
This approach provides transparency and allows both manufacturers and specifiers to see where the main sources of environmental issues occur. In addition to these modules, the completed EPD certificate also includes information about the PCR (such as what boundaries have been set and which stages in a product’s lifecycle are covered), along with general information about the product and manufacturing process.
The final stage is used to evaluate the study, identify any limitations and ultimately ensure that the data collected is accurate and has been evaluated correctly. It also allows the data gathered to be used to assist the manufacturer in identifying areas for improvement in the future and to set targets for these.
How are EPDs for construction products changing?
As mentioned earlier, all EPDs within the UK are completed under the core PCRs within the harmonised standard EN 15804. This standard was first introduced in 2012 and has received two significant amendments since its publication, the first (EN 15804+A1) in 2013 and more recently in 2019 (EN 15804+A2). In addition to improving how the EPDs function, these amendments also reflect changes in our understanding of environmental impacts from construction and the growing focus on end-of-life and circularity.
With the introduction of EN 15804+A2, new EPDs have been expanded to require reporting to 13 core indicators:
- Global warming potential (GWP) total
- GWP fossil fuel derived
- GWP biogenic – carbon cycle within natural systems (for example, CO2e from forestry industry, taking into account carbon removed by people when the tree is cut down)
- GWP land use change – (such as grassland used to produce silage turned into a housing estate)
- Eutrophication in fresh water
- Eutrophication in marine water
- Terrestrial eutrophication
- Ozone depletion
- Photochemical oxidation potential – NOx and volatile organic compounds (VOCs)
- Abiotic resource depletion: minerals and metals
- Abiotic resource depletion: fossil fuels
- Water use deprivation.
In combination with a further six additional environmental indicators, these allow more in-depth analysis of product performance for manufacturers. For example, GWP was previously reported under a single identifier. By separating this out into four sections, it is possible for manufacturers to be more targeted when looking for ways to raise the performance of products. This added detail also supports building LCA approaches in accurately modelling how the environmental impacts of a structure may change across its lifespan.
Perhaps more significantly, while under EN 15804+A1 it was possible to publish EPDs solely on the basis of cradle-to-gate analysis (modules A1-3), it is now mandatory for virtually all products to also include modules C1-4 (end of life) and D (reuse/recycling). This cradle-to-gate with options approach reflects growing concerns about the volume of waste generated by the construction industry and the impact this may be having on our environment.
By making these sections compulsory, manufacturers must now give more consideration to the waste streams that a specific product goes into and how these can be reduced. In practice, this can include adjusting the chemical composition of products, making changes to the production process to limit waste outputs, and operating waste take back schemes.
The inclusion of module D (recycling/reuse) takes this one step further, requiring manufacturers to begin to apply circular business models. The calculation methods used for this section have also been revised to allow more detailed analysis. These changes may mean that manufacturers take steps to adapt the design of products, for example by utilising more recycled content as part of new products. It will also mean looking into alternative routes to deal with products at the end of the building’s life such as upcycling, downcycling, reuse or energy-from-waste solutions.
How can EPDs be used within building LCAs?
One of the key challenges in using the data from EPDs to generate a building LCA is that the impacts for the different construction products need to be accurately weighted by the quantities of material actually expected to be used on the building. For example, the environmental impacts for an insulation material used throughout a building’s walls will need to carry proportionally more weight than those for a flooring material restricted to a single room.
Tools used to generate whole-building assessments typically overcome this obstacle in a couple of ways. The software first incorporates a database of product environmental impact data taken from different sources including EN 15804+A2 EPDs. The tools then plug-into advanced BIM software, which is able to identify the products specified for a project and their estimated quantities. By taking the quantity data from the BIM model and multiplying it by the environmental impact data within their databases, the tools are able to generate a whole-building assessment of environmental impacts.
BRE Global is aiding the development of these tools through Impact, a specification and database of product LCA data which can be used by software developers to create whole-building assessment tools. Impact-certified tools are able to report environmental indicators separately or allow them to be combined into BRE ecopoints. They also allow the environmental impact of a building to be assessed at different stages in its lifespan. This can highlight, for example, the added environmental impact of materials or technologies with shorter serviceable lives.
Impact-certified tools can also be used in conjunction with other software that calculates the expected operational energy and water demand for a building. This provides project teams with a comprehensive view of the expected environmental impact of a building, allowing them to adjust specifications to optimise whole‑life performance.
It is also hoped that early adopters of these building LCA approaches will help to facilitate practice among later users through benchmarking. An initial benchmarking exercise was carried out during the development of Impact to provide a representative average for users to assess their own building against. BRE Global anticipates that project teams who use Impact‑certified tools as part of their BREEAM assessment will also submit their BIM models for analysis and benchmarking. This will allow the benchmarks to be raised over time, driving improved practice.
A complete view of environmental impact
The development of digital technologies such as BIM is creating a variety of new possibilities and opportunities for the construction industry. In addition to streamlining processes and improving communication, they can also support the creation of data-rich environments that allow significant amounts of detailed information to be stored and processed rapidly and accurately.
By incorporating the detailed data from EPDs into these models, we can now gain even greater insights into how our buildings are expected to interact with and impact the environment. This approach can help to drive forward best practice both within construction and manufacturing, helping to deliver a built environment which offers improved value and leads the way in addressing environmental concerns such as climate change.