BRE Global has recently published their approach to the new standard developed by CEN/TC 350, EN 15804, which sets overarching Product Category Rules for EPD. The full document was originally circulated to the Construction Products Association Sustainable Construction Committee in November 2011 and a shorter statement is also available.
BRE Global have undertaken a comparison of the methodologies for life cycle assessment of construction products provided in EN 15804 (to be published through BSI later this month) and the 2007 update of the BRE Environmental Profiles Methodology. This comparison is not available in the public domain however and the basis of the comparison (ie materials studied, weightings used, treatment of recycling beyond the system boundary (Module D) is unknown). The study apparently included a comparison of the environmental performance for a wide range of construction materials using both methodologies, which showed that “whilst the absolute results may differ, the relative performance remains the same”.
BRE Global states that “there is enough overlap in the environmental, resource use and waste parameters measured by the two approaches to ensure that the BRE Global method meets the requirements of TC 350”. Following on from this, and as a result of the finding that the relative performance of products remains the same, BRE Global have decided to continue to use the existing Green Guide Online, based on the Environmental Profiles Methodology in BREEAM, but to provide EPD in the future to both the Environmental Profiles and EN 15804 Methodologies.
I am afraid I have to disagree with BRE – there are too many differences from TC 350 for me to consider that the BRE Global method meets the requirements of TC 350.
How much difference is there between the BRE Global method and TC 350?
The table below highlights the key differences between the two methods, some of which could have significant difference for particular materials.
|Environmental Profiles||CEN/TC 350 EN 15804|
|System Boundary||Point where the next system starts to pay for waste, by-products, co-products or recycled material||Point at which the waste reaches the “end of waste” state (based on Waste Framework Directive). For outputs which are never waste system boundary occurs at point of production.|
|Allocation to End of Life Recycling||Yes, by value, based on value of scrap arising after demolition and value of “basic material”, eg aluminium ingot, steel slab.||No. But benefits of recycling beyond the system boundary can be shown in “Module D” and may be included in building level assessments|
|Replacement Factor calculation||Service life used to provide probabilistic replacement factor (ie 30 year service life would mean 100% of product replaced by year 45, 150% replaced by year 60 and 200% replacement by year 75.)Methodology assumes 60 year study period but demolition can occur any time after.||Service life used to provide deterministic number of replacements – eg a service life of 30 years will mean complete replacement in year 30 and year 60. EN 15978 allows for replacements close to the end of the building life to be omitted if they wouldn’t happen in reality.Study period based on building life required by client or regulation, and demolition happens at the end of the study period.|
|Toxicity (human , ecotoxicity to fresh water and to land )||Included (25.4% of Ecopoints weighting)||Not included|
|Minerals extraction||Included – total mass of minerals extracted (9.8% of Ecopoints Weighting)||Not included|
|Abiotic Depletion Elements||Not included||Included – measure of scarcity of chemical elements such as metals|
|Nuclear Waste||Volume of intermediate and high level nuclear waste measured (8.2% of Ecopoints weighting)||Total mass of low, intermediate and high level nuclear waste measured (low level waste is majority of overall nuclear waste)|
|Use of renewable primary energy||Indicator not included||Included (split into feedstock and energy use)|
|Use of non-renewable primary energy||Fossil Fuel use included (3.3% of Ecopoints weighting)||All non-renewable primary energy use considered (includes nuclear energy)|
|Use of secondary materials and fuels||Indicators not included||Indicators included.|
Would the relative performance of materials really not change if the TC 350 methodology was used?
Without access to the BRE materials database or sight of the research, it is impossible to be certain of this, but in my view, it is unlikely for the following reasons:
- The BRE indicators not included within EN 15804 account for at least 35% of the weighting in Ecopoints and are significant contributors to overall ecopoints for many materials. BRE have also not provided any indication of how they have weighted the EN 15804 indicators which were not used by BRE, such as abiotic depletion or use of renewable energy.
- Although the BRE Minerals extraction category and the EN 15804 Abiotic Depletion Elements category both relate to resource depletion, they are highlighting very different issues. The BRE Minerals extraction impact relates to the total mass of material extracted from the environment, whereas the Abiotic Depletion Elements category relates to the scarcity of chemical elements within the earth’s crust, and the rate of depletion.
- Additionally, there are significant methodological differences in terms of system boundary, allocation to end of life recycling and replacement factor calculation that vary between the two systems, and BRE has not stated if or how they have been considered.
- For treatment at the end of life, there will be significant differences for the EN 15804 methodology depending on how BRE consider the benefits beyond the system boundary shown in Module D – again we don’t know how BRE have considered this.
BRE Global states that “there is enough overlap in the environmental, resource use and waste parameters measured by the two approaches to ensure that the BRE Global method meets the requirements of TC 350”. Does the approach used in Environmental Profiles, the Green Guide and BREEAM meet the requirements of TC 350?
- In my opinion, it does not, for the following reasons:
- Environmental Profiles and the Green Guide are not based on a CEN/TC 350 compliant methodology, as shown by the significant differences highlighted above. Without publication of the analysis which underlies BRE’s claim that “the relative performance remains the same” it is difficult to take this at face value.
- Green Guide ratings are based on typical specifications. At present, if the specification listed in the Green Guide matches the one used in the building in terms of materials, then the Green Guide rating can be used. This does not take into consideration differences in thicknesses or spacing of materials, exposure of the actual building and the effect this might have on service life, or real site waste management or transport strategies.
- BREEAM currently uses the midpoint ecopoints score for each Green Guide rating together with the area of elements to calculate the overall building impact, and hence the amount of credit. The CEN/TC 350 approach is intended to provide a full building life cycle assessment, taking account of the actual specifications and materials used, including building structure, foundations and building services. As BRE state, Green Guide is a useful guide to the relative impact of constructions, but it not a mechanism to provide building level LCA as required by CEN/TC 350.
- Because BREEAM credits are not provided for the foundations, core building structure and building services, a significant proportion of the building impact is not being considered.
- CEN/TC 350 also requires that the effect of construction products at the building level is taken into consideration. Again, because of the elemental nature of the Green Guide assessment, the effect of heavier cladding and floor decks on the structure and foundations or the embodied impact of different types of building services equipment cannot be assessed or considered within Green Guide and hence a significant aspect of CEN/TC 350 is ignored.
What about the barriers to trade CEN/TC 350 was supposed to remove?
- The CEN/TC 350 standards were mandated by the European Commission to remove the barriers to trade that have existed for manufacturers whilst countries use their own incompatible national EPD schemes. By continuing to use the Green Guide to assess materials, BRE Global are maintaining a considerable barrier to those with EN 15804 compliant EPD from outside the UK, in terms of competing on the basis of their product’s actual life cycle environmental performance. For those working with the Environmental Profiles scheme, costs will be increased because they will need to produce EPD to the two methodologies.
By maintaining the use of the Environmental Profiles Methodology and the Green Guide based on it, BRE Global continue to operate independently of other European EPD schemes which are fully adopting TC 350, and they are providing a barrier to trade for European producers with other EPD who cannot use these directly within BREEAM. For producers using BRE Global to produce EPD, costs will be increased as two separate EPD and LCA models will need to be produced to take account of the two different Methodologies.
Whole building LCA, based on TC 350 is the mechanism which we should be using to ensure that we are correctly addressing the reduction of environmental impact from buildings which is required – this is the only approach which will ensure operation and embodied impacts are balanced, and that the complex interplay of different construction choices are considered in the whole. Unfortunately, the BRE Global approach does not currently meet this objective.