The Embodied Carbon Group                            SBE0062

Written evidence submitted by the Embodied Carbon Group

 

Executive Summary

The UK built environment plays a key role in helping the government to achieve their plans to reduce carbon emissions by 78% by 2035 and 100% by 2050. In order to do this though, the construction industry must have a series of Whole Life Carbon (WLC) requirements imposed on it.

There is a need to mandate WLC assessments for all construction as part of planning and building regulations, as soon as possible. Assessment codes, standards and methodologies are already in place for this, and the industry is already upskilling in adopting these assessment methods into a normal part of design and construction practice.

These assessments give a holistic view of the carbon emissions associated with the construction, use and deconstruction of a built asset such as a new home or school.

 

To what extent have the Climate Change Committee’s recommendations on decarbonising the structural fabric of new homes been met?

The CCC recommends developing policies to minimise whole life carbon (WLC) impact of buildings.

There are currently no specific policies in place that target the WLC impact of new homes. Whilst the Future Homes Standard focusses on reductions in operational energy, it does not refer to embodied carbon, which can be around half of the whole life carbon of a well-designed home. Greater incentives are also needed to encourage not building anything new at all and instead retrofitting, which is the lowest embodied carbon option. Again, this is not mentioned in the Future Homes Standard

The CCC also mentions timber specifically. It should also be noted that whilst timber can often be used to minimise WLC, this isn’t always the case. WLC assessments take a holistic view of the sum total of upfront embodied carbon (e.g. product manufacture), in-use embodied carbon (e.g. replacements), in-use operational carbon (e.g. energy use), and end-of-life carbon (e.g. demolition). Whilst the use of timber and other bio-materials can minimise upfront carbon emissions, they may need to be replaced more often during the life of the building, and so this must be accounted for in the overall carbon assessment.

WLC assessments also introduce the need for the design team to consider not just the materials that they use, but also how they are used. Efficient, simpler configurations of structure and façade lead to dramatic decreases in the embodied carbon of those components, regardless of which material they are made in.

Requiring WLC assessments for all construction would be the most effective way to respond to the CCC’s recommendation to develop polices that minimise WLC impact of buildings. These assessments target both materials and efficiency, have standardised methodologies and procedures, and the UK construction industry is rapidly upskilling in undertaking assessments as part of the design process (driven largely by the organisations represented by this group).

 

How can materials be employed to reduce the carbon impact of new buildings, including efficient heating and cooling, and which materials are most effective at reducing embodied carbon? 
What role can nature-based materials can play in achieving the Government’s net zero ambition?

The ideal design solution will minimise upfront embodied carbon to reduce emissions today, whilst also minimising whole-life carbon to avoid the need to emit more carbon than is necessary in the future.

Efficient use of wood and other nature-based materials can lead to a reduction in the upfront embodied carbon of a project. However, again it should be noted that the amount of material is just as important as what that material is. For example, timber is most efficient over short spans, and so could be an inefficient choice for a building requiring larger distances between columns or walls.

Choice of material will also be driven by their whole-life carbon footprint. For example, the use of a natural insulation material may emit less carbon today, but may need replacing more often (and be less suitable for re-use after demolition) than a synthetic alternative.

In both examples, a whole life carbon assessment is needed in order to identify what the overall lowest carbon solution is, rather than just identifying the lowest carbon material.

Mandating this approach of assessing carbon and interrogating what happens about the carbon/cost benefits through the lifetime of the project would result in low carbon solutions in the most holistic sense. In many cases, this will involve the use of nature-based materials – but not always.

 

What role can the planning system, permitted development and building regulations play in delivering a sustainable built environment?
How can these policies incentivise developers to use low carbon materials and sustainable design?

Legislation mandating whole life carbon assessments for all construction projects over a certain size is going to be needed as part of both planning and building regulations if the government wishes to meet its 78% emissions reduction target by 2035.

At this current time, individual project decisions continue to be driven by cost and time – typically with minimal serious consideration of embodied carbon emissions. If this practice continues, it is unlikely that the construction industry will decarbonise at the pace required to contribute to the 2035 target.

Designers need to be incentivised not just to specify low carbon materials, but to design holistically with them towards an overall low carbon solution. The same low-carbon thinking must be followed through onto site, without mistakes, with construction and details that last.

UK producers need to be encouraged to invest in low carbon technology, and to provide Environmental Product Declarations (EPD, a report that quantifies environmental information on the life cycle of a product) to demonstrate that their product is the best one.

Introducing whole life carbon assessments and targets will encourage all of these behaviours, improving both the design and construction, with all parties working together to reduce the industry’s emissions.

 

What methods account for embodied carbon in buildings and how can this be consistently applied across the sector?

A well-established series of standards are recognised across the industry. These are: EN 15978 (assessment of environmental performance of buildings), EN 15804 (construction products), and the RICS Professional Statement on whole life carbon assessment for the built environment.

The UK’s Professional Institutions such as the RIBA, IStructE and CIBSE are currently upskilling their members in understanding and utilising these codes and standards, and in coming years will mandate the ability to design with them. Wider industry groups including CIC, CLC, Construction Declares and LETI are pursuing similar initiatives and providing industry with further guidance.

Whole life carbon assessment legislation in alignment with these standards would be welcomed across the construction sector.

 

Should the embodied carbon impact of alternative building materials take into account the carbon cost of manufacture and delivery to site, enabling customers to assess the relative impact of imported versus domestically sourced materials?

This is accounted for within the standards listed above, which include an assessment of the emissions due to transportation to site. The significance of this varies depending on material type and transport distance.

Note that transport is only one part of the bigger picture. A whole life carbon assessment also includes the impacts of extraction, transport and manufacturing, wastage on site, construction impacts, maintenance, repair, and replacement, and predicted impacts at end of life. The standards shown above have established methodologies for all of these.

 

How well is green infrastructure being incorporated into building design and developments to achieve climate resilience and other benefits?

Green infrastructure measures such as sustainable drainage, green and blue roofs, urban reforestation and on-site compositing can all bring benefits beyond just carbon – such as cooling through transpiration and evaporation and reducing sewage into rivers. Measures to incorporate these wider benefits should be considered across all projects, and so the value of these must be assessed in some way as part of the appraisal process.

WLC assessments are building-focussed, but the same assessment approach should be applied to urban infrastructure as well, and the government should consider ways in which this can be implemented. This would ensure that projects such as housing schemes, business parks and masterplans are designed in a way to minimise the carbon of the entire project, rather than just for individual buildings.

 

How should we take into account the use of materials to minimise carbon footprint, such as use of water harvesting from the roof, grey water circulation, porous surfaces for hardstanding, energy generation systems such as solar panels?

All of these systems should be assessed, either within the assessment of the building if they are provided as part of the building, or as an assessment of the overall development. The energy and water savings resulting from all of these would be determined as part of a Whole Life Carbon assessment.

Note that whilst these ‘additions’ can help to minimise water and energy use of the building, they will not do anything to reduce the embodied carbon of it. Embodied carbon reductions are better driven through simpler, more efficient designs, with the right materials selected for the job. Introducing mandatory carbon targets will result in design teams implementing these strategies as a core part of their response to design briefs.

 

How should re-use and refurbishment of buildings be balanced with new developments?  What can the Government do to incentivise more repair, maintenance and retrofit of existing buildings?

The biggest embodied carbon reductions come from reusing and refurbishing existing buildings. Embodied carbon savings of 50% are possible, as you do not need to construct a new building structure and envelope. This is often accompanied by cost and time savings. Reuse should be prioritised wherever it leads to a lower whole-life carbon footprint for the building.

Removing VAT on repair and retrofit would provide an immediate financial incentive. Carbon targets will also incentivise this behaviour; with reuse being the quickest route to a low embodied carbon footprint. Longer-term, the government should consider linking VAT in construction to a project’s Whole Life Carbon assessment (kgCO2e/m2) as part of a polluter-pays principle. Reuse projects, with their inherent low-carbon credentials, would be prioritised.

 

The Embodied Carbon Group

We are pleased to have been given the opportunity to respond to the Environmental Audit Committee’s call for evidence on Sustainability in the Built Environment.

The Embodied Carbon Group are a group of UK embodied carbon leaders and experts.

We offer our advisory services to help the UK Government achieve its stated goals of 68% GHG reduction over 1990 levels by 2030, 78% by 2035, and net zero carbon by 2050, and to offer our input where required to achieve interim deliverables in the run-up to the UN COP26 climate talks.

Our embodied carbon expertise spans the full field of topics including calculation methodologies e.g. LCA, standards and regulation in the UK and abroad, assumptions and availability of information including EPDs, design and design drivers, and cost/carbon optimisation.

The Embodied Carbon Group members are:

The Embodied Carbon Group is coordinated by Tim den Dekker (Feilden Clegg Bradley Studios).

 

May 2021