As regulation and voluntary measures such as BREEAM and the Code for Sustainable Homes have looked to reduce operational carbon, there has been an increasing focus on embodied carbon – the carbon which is associated with the materials in the building. Embodied carbon normally encompasses both CO2 and other greenhouse gases, and includes emissions from all the extraction, transport and manufacturing processes required before products are ready at the factory for delivery to the customer – such an assessment is known as “cradle to gate”. It can also cover transport to site (“cradle to site”), installation impacts (including the impact of dealing with construction waste) (“cradle through construction”), maintenance such as cleaning, repairs, replacement and refurbishment of products, and the impacts associated with the product’s end of life, such as demolition, recycling and disposal. If all the life cycle stages are included, then the assessment is known as “cradle to grave”, although this doesn’t mean that the assessment assumes products are landfilled. If products are normally recycled at end of life, then a “cradle to grave” assessment would account for this, but ensuring (in line with ISO 14044) that the benefits of recycling for a material are not double counted for both the use of recycled content and its recycling at end of life.
Embodied carbon in the UK
The UK was one of the first countries to recognise the significance of the energy used to make construction products, called embodied or embedded energy, and to collect data and statistics from industry. The UK was also a leader in developing Life Cycle Assessment to look not just at the embodied energy, but the resulting environmental impacts and process emissions throughout the supply chain and life cycle. This led to the development of “Environmental Profiles” for construction products, with the reported climate change or global warming impact providing the embodied carbon data. BRE published a national methodology for assessing the cradle to grave environmental impacts of construction products with the Environmental Profiles Methodology published in 1999. Based on this methodology, and using data provided by the UK construction products industry, the Green Guide to Housing Specification (BRE, 2000) provided embodied assessment of over 200 building elements used in housing which was used within EcoHomes to assess the Mat 01 credit.
As other countries developed their own methodologies for measuring the embodied impacts of construction products, international standardisation followed with ISO 14025 covering Environmental Product Declarations (EPD) generally in 2006, and ISO 21930 covering EPD for construction products in 2007. The standards encompassed the many approaches found nationally however, and manufacturers were faced with a situation where different EPD schemes operated in in each country, meaning increased costs and confusion in the market as the same product could have different impacts depending on which EPD scheme was used.
Harmonising approaches across Europe
Recognising this challenge, the European Commission mandated the European Standards organisation, CEN, to develop horizontal standards for harmonising the assessment of environmental impacts associated with construction products and buildings. The resulting CEN/TC 350 series of European Standards have been developed and published with cross-industry involvement and consultation, giving a common methodology for providing EPD across Europe in EN 15804 and linking to a common methodology for the assessment of building Life Cycle Assessment (LCA) in EN 15978. EPD schemes in the UK, France, Germany, the Netherlands, Sweden, Norway, Spain, Portugal, Italy and the United States have now adopted the EN 15804 standard and offer compliant EPD. The European schemes are united through the ECO Platform organisation, and there has been a rapid rise in the number of EPD, with over 2000 EPD now available within ECO Platform programmes and mutual recognition schemes in place for several of the members.
Environmental Product Declarations (EPD)
EPD to EN 15804 must also comply with the requirements of ISO 14044, the International Life Cycle Assessment (LCA) standard, and ISO 14025 and ISO 21930, the International standards covering EPD for construction products. These three standards, together with the more detailed requirements of EN 15804 in terms of exact application of LCA principles, mean that EPD produced to EN 15804 are consistent and can be used to compare products at the building level. EPD according to ISO 14025, and hence EN 15804 need to be verified by an Independent Verifier, who has not been involved in the EPD project, who does not have conflicts of interest arising from their position and who has experience of Life Cycle Assessment and a knowledge of the product being assessed.
Figure 1: Life cycle stages and modules used in CEN/TC 350 standards such as EN 15804
EN 15804 provides life cycle impact assessment (LCIA) data for the product in a series of modules covering the various life cycle stages, described in Figure 1.
Data are only required to be reported for Modules A1-A3; provision of data for all other life cycle stages is voluntary. Any data that are provided for the life cycle stages beyond the Gate (A3) are based on scenarios, and users of EPD need to check whether the scenario described for the product is relevant for the building in which they are using the product.
For example, an EPD for a product manufactured in Germany may provide a scenario for transport to site (A4) in relation to a German customer which would not be correct for transport to a customer in Scotland. Similarly, the reference service life and maintenance provided for the product may relate to a sheltered position in central Germany, and not be relevant to installation in the north elevation of a building in an exposed coastal location such as Aberdeen. Furthermore, the end of life scenario may be based on typical disposal in Germany, where the end of life material would be used for energy recovery, whereas in the UK, the end of life product would typically result in a mix of recycling and landfill.
Over time, national tools and databases to generate or provide these scenarios should become available – for example, thinkstep has recently worked with the UK timber industry to produce LCA datasheets providing cradle to gate, distribution and end of life data for the different disposal routes used by timber products used in the UK, and with the steel industry to provide end of life datasets for structural materials used in the UK.
Other countries, such as the Netherlands and Germany, have published national databases of LCA data for construction products and included mandatory building level LCA within their Building Regulations (Netherlands) and within DGNB (the equivalent of BREEAM in Germany). However, although such a database exists in the UK, developed with UK manufacturers data provided through the Environmental Profiles project, this remains outside of the public domain whilst BRE and manufacturers debate ownership.
In this vacuum, the Inventory of Carbon and Energy (ICE), a cradle to gate database (examples: see below) derived from a literature review of freely available environmental data by SERT at Bath University and now held by Craig Jones’ consultancy, Circular Ecology, has remained the default source of embodied carbon data for construction products and has meant that building level embodied carbon assessments rather than LCA studies are the norm here. The ICE database provides embodied energy and embodied carbon data for over 200 construction materials, but it has some limitations, namely:
· it only covers cradle to gate,
· it does not include any manufacturer specific data (such as that provided in EPD),
· it has not been updated since publication in 2011,
· many of the underlying studies used for the database are much older than this,
· some datasets are based on only a few, or even just a single, published study,
· datasets have often been produced based on adaptation of studies which provided data for other countries, or that provided only energy data, and/or used very different methodologies in terms of system boundaries and allocation.
· No mechanism for manufacturers or trade associations to provide UK specific data has been made available.
Circular Ecology is hoping to overcome some of these limitations if funding can be found, but in the meantime, the ICE database remains the most consistent embodied carbon dataset for the UK.
Building level embodied carbon
EN 15978, the CEN/TC 350 building level LCA calculation standard, requires the assessment of all the TC 350 indicators over the full building life cycle. As ICE only provides cradle to gate data for embodied carbon, industry has struggled to take building LCA forward in the UK. As a result, a wide range of different approaches has been used but we are now seeing some consolidation, as the RICS have provided a free information paper giving a clear approach to cradle to gate assessment of embodied carbon of building, and a guidance note for their global members covering the evaluation of building level embodied carbon. The GLA has also published a guide to assessing embodied carbon of buildings which covers the full life cycle.
All these methodologies state that they are aligned to the TC 350 standards in terms of methodological aspects, with the exception of only measuring embodied carbon, rather than the 24 environmental indicators required by TC 350.
Building Level Embodied Carbon tools
BRE’s Envest tool was one of the first embodied carbon tools, first sold in 2002, but had little uptake in the market. The Environment Agency has developed a simple free embodied carbon tool, covering cradle through construction. In 2009, the Technology Strategy Board funded the development of a range of embodied carbon tools through its Low Impact Buildings call, but at present, only IES’s IMPACT tool is commercially available. In other countries, a range of cradle to grave LCA tools are available. For example, the Dutch government has approved a number of tools for use in its regulated embodied impact assessment for new housing and office buildings. In France, Elodie has been developed to use the numerous French FDES environmental declarations to provide a building LCA for HQE. thinkstep's GaBi Build-it is used in Germany as part of the mandatory Building LCA within DGNB. In the United States, Tally® has been developed as a BIM Plugin to provide building LCA with North American EPD and LCA data provided by thinkstep.
At the moment, many of these tools use different databases and slightly different scopes, although all report embodied carbon (may be reported as Global Warming Potential, GWP or Climate Change), allow the main building elements to be assessed, and cover cradle to gate and end of life. WRAP has launched an Embodied Carbon Database for building level data, which allows you to compare the embodied carbon results for your building against others with a similar scope in terms of life cycle stages and building elements. Over time, WRAP hopes to be able to provide national benchmarks using data from this database.
Top tips to reduce Embodied Carbon
1) Focus on the elements of the building with highest impact: have a look at the links to case studies below to identify these.
2) Look at the form of the building – can you reduce the amount of key elements by changing the design of the building?
3) Investigate ways to increase the resource efficiency of these elements, for example research by Cambridge University suggests buildings commonly use double the steel and concrete that is required by safety codes.
4) Consider alternative materials that can do the same job – the Green Guide Online lets you compare the overall environmental impact and embodied carbon of similar building elements.
5) Look at increasing the recycled and by-product content of the materials you are using – for example increasing the use of alternative cementitious materials like PFA and GGBS in concrete reduces its impact significantly.
6) Examine environmental information provided by different suppliers – such as EPD or carbon footprints. Will their products have lower impact in your building?
For embodied carbon case studies, look at my @constructionlcalinks on Delicious.
For further information on reducing embodied carbon, look at WRAP’s guidance.
For further information on increasing recycled content, look at WRAP’s guidance.
For comparable EN 15804 EPD in English, look at IBU, International EPD and BRE.
Further information and guidance on embodied carbon and resource efficiency can also be found using the links below.
 BS ISO 14044:2006 Environmental management — Life cycle assessment — Requirements and guidelines
 BS ISO 14025:2006 Environmental labels and declarations — Type III environmental declarations —Principles and procedures
 ISO 21930:2007 Sustainability in building construction — Environmental declaration of building products
 BS EN 15804:2012+A1:2013 Sustainability of construction works — Environmental product declarations — Core rules for the product category of construction products
 BS EN 15978:2011 Sustainability of construction works — Assessment of environmental performance of buildings — Calculation method
 www.milieudatabase.nl/index.php?id=home and www.nachhaltigesbauen.de/baustoff-und-gebaeudedaten/oekobaudat.html
 RICS Members only: www.rics.org/uk/knowledge/professional-guidance/guidance-notes/methodology-to-calculate-embodied-carbon-global-guidance-note-1st-edition/
Sustainability, from consulting to software.
Sustainability awareness is the road to long-term corporate operation and a vibrant environment. thinkstep has been steadily guiding companies all over the world along this road since 1991. Today, thinkstep is the international market leader in strategic consultancy, software solutions and extensive services in the field of sustainability.
Serving market leaders around the world, thinkstep has offices in Stuttgart, Vienna, Zurich, Copenhagen, Sheffield, London, Tokyo, Taipei, Perth, Bhilai, Boston, Wellington, Shanghai, Johannesburg, Istanbul and Kuala Lumpur.
thinkstep provides conscientious companies with cutting-edge tools, in-depth knowledge and an unparalleled spectrum of experience in making both corporate operations and products more sustainable. Applied methods include implementing management systems, developing sustainability indicators, life cycle assessment (LCA), carbon footprint, design for environment (DfE) and environmental product declarations (EPD), technology benchmarking, or eco-efficiency analysis, emissions management, clean development mechanism projects and strategic CSR consulting.
Moreover, thinkstep offers two leading software solutions, with the GaBi software for product sustainability and the SoFi software for corporate sustainability. Over 2500 companies and institutes worldwide put their trust in thinkstep’s consultancy and software, including market and branch leaders such as Alcan, Allianz, Bayer, Daimler, Deutsche Post DHL, Rockwool, Siemens, Toyota, ThyssenKrupp and Volkswagen.
Author: Jane Anderson, Principal Consultant, thinkstep.
Jane Anderson is one of the UK’s leading experts in the embodied impacts of construction materials, having worked on Life Cycle Assessment and EPD for construction products for over 15 years. She led the development of the 2007 update of the BRE Environmental Profiles Methodology, and co-authored the original BRE Environmental Profiles Methodology published in 1999 and all of BRE’s Green Guides to Specification from 2000. She is the UK expert on CEN/TC 350 WG3, the working group which developed the European Standard, EN 15804, providing a consistent set of rules for EPD for all construction products across Europe. With thinkstep, she has recently worked on the development of an EPD and EPD tool for UK cement for the Mineral Products Association, the Wood for Good Lifecycle database for the UK timber industry and has just started work on a trade association EPD and tool project for precast and ready mixed concrete in the UK. With Jane Thornback, she wrote the Construction Product Association’s “Guide to understanding the embodied impacts of construction products”. She tweets and blogs as @constructionlca.
Examples of embodied carbon
The figures included in the following table are a much-shortened and abbreviated adaptation of a survey published by the Sustainable Energy Research Team (SERT) of the University of Bath. The survey, ‘Inventory of Carbon & Energy (ICE)’ V2.0, was compiled and written by Prof. Geoff Hammond & Craig Jones, 2011. The full detailed survey, complete with original data, methodology and notes, is available from www.circularecology.com/ice-database.html
The figures are based on a ‘Cradle-to-Gate’ analysis of publicly available information.
|Concrete (1:1.5:3 eg in-situ floor slabs, structure)
|Concrete (eg in-situ floor slabs) with 25% PFA RC40
|Concrete (eg in-situ floor slabs) with 50% GGBS RC40
|Concrete block (Medium density 10 N/mm2))
|Rammed earth (no cement content)
|Cement mortar (1:3)
|Steel (general - average recycled content)
|Steel (section - average recycled content)
|Steel (pipe - average recycled content)
|Timber (general - excludes sequestration)
||480 - 720
|Glue laminated timber
||700 - 800
|Cellular glass insulation
|Cellulose insulation (loose fill)
||0.94 – 3.3
|Glass fibre insulation (glass wool)
|Expanded Polystyrene insulation
||15 – 30*
|Polyurethane insulation (rigid foam)
|Woodwool board insulation
|Wool (recycled) insulation
||100 – 110*
|Mineral fibre roofing tile
|Slate (UK – imported)
||0.1 – 1.0
||0.006 – 0.058
|Aluminium (general & incl 33% recycled)
||0.38 - 0.43
||600 - 1000
||680 – 760*
||540 - 700
|Carpet tiles, nylon (Polyamide), pile weight 770g/m2
||13.7 / m2
|Wood stain / varnish
|Vitrified clay pipe (DN 500)
|Iron (general )
|Copper (average incl. 37% recycled)
|Lead (incl 61% recycled)
|Ceramic sanitary ware
|1200 x 1200 2x glazed, air or argon filled
||MJ per window
||2150 - 2470
||110 - 126
|Aluminium clad timber frame
||950 - 1460
||48 - 75
||230 - 490
||12 - 25
||230 - 490
||12 - 25
|Krypton filled add:
|Xeon filled add:
Photovoltaic (PV) cells
|Thin film (average)
Key: * - figures byGreenSpec obtained from publicly available information
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