Embodied carbon…the elephant in the room?

by Francesca

The much anticipated consultation document ‘The Future Buildings Standard’ is provoking a mixed response from experts. Whereas the document proposes a welcome doubling down on the amount of energy used in a building during its lifetime operation, ‘operational carbon’s’ less headline-grabbing cousin ‘embodied carbon’ doesn’t even get a passing nod in the 114 page paper.

‘Embodied carbon’ is a component of the total carbon consumed by a building; Before anyone moves into a new house, office or factory, a significant amount of energy has already been expended on the construction of the building including its components and their transportation to site. The proportion of ‘embodied carbon’ varies, but it’s estimated that on average the figure represents around 19% of the ‘Whole Life Carbon’ total building emissions;  In turn the total carbon output from the nation’s buildings amounts to a sobering 42% of all UK emissions.

In the days before the oil crises and the introduction of Part L of the Building Regulations, embodied carbon would have barely notched a percentage point against the colossal expenditure of fossil-fuel derived energy powering our buildings. But as the ‘Regs’ continue to squeeze energy waste, embodied energy equally grows as a proportion of total carbon expenditure. As Part L cracks down further through the ‘Future Buildings Standard’, carbon emitted during construction will be hard to miss. The ‘elephant in the room’ will have to be confronted.

 ‘Embodied carbon’s’ omission from the consultation paper is therefore remarkable, given its increasing magnitude. Industry professionals have greeted the exclusion with concern: Architect Seb Laan Lomas, coordinator of the Architects Climate Action Network (ACAN)’s embodied carbon group, said the government had recognised the clamour for embodied carbon to be part of the Future Homes Standard (FHS) but that its response was inadequate. “The government shockingly fails to mention embodied carbon a single time in its own response,” he said. “The industry urgently needs greater commitment on this roadmap from the government, as in the absence of regulation, these upfront emissions continue to have a damaging toll.”

1. Diagram showing the life cycle of construction materials, the CO2 arrows indicate the predominant effect on carbon contributions.

Other industry bodies including London Energy Transformation Initiative (LETI). Architects Declare (AD), UK Green Building Council (UKGBC) and the Alliance for Sustainable Building Products (ASBP) have echoed concerns about the omission of a mechanism to calculate embodied carbon including  The RIBA president Alan Jones who has also publicly criticised the Government’s failure to include a requirement to calculate the operational energy or embodied carbon of new homes within the proposals.

So what’s going on? Responses to the government’s proposals haven’t yet been published, but one leaked document from a large house builder provides a clue: in being less than enthusiastic about future standards, the company bleats out  its standard old-chestnut faux consumer objection: ‘expensive’ energy conservation – but it goes on: “There is a lack of evidence to support the viable delivery of the future homes standard of 75-80% less CO2 emissions within the proposed timescale with existing skills training and supply chain availability.” They might have something – It’s been clear to all construction industry observers over the 50 years that training and knowledge have not kept up with the demands of evolving construction technology. The house builder probably knows best that its site employees and building designers are way behind in supplying the building performances expected of the proposed Part L changes. And that’s just  Part L, the operational energy section. The company just says “Effectively we can’t do it”.

Sure, we’re tempted to treat that with a pinch of salt, but the industry is notoriously slow in changing direction. Historically just small changes in performance take time, commitment and legislation to happen. Maybe in the scheme of things, the government whilst unofficially recognising the obvious importance of embodied carbon reckons that it’s already complicated enough just upping the weaponisation of Part L. A cynic also might also point out that it just can’t bring itself to deliver a more onerous message to the ‘put-upon’ developers – who maybe just happen to be amongst the current government’s main party donors!

The news that the consultation document ‘The Future Buildings Standard’ fails even to acknowledge the contribution of ‘embodied carbon’, will come as no surprise to seasoned industry observers. It follows a pattern of first climate change denial, a dragging of feet towards accepting first the problem and then the need to act to meet the government’s own carbon reduction targets.

It’s tempting to think that there might be a council of despair and disappointment, but that most certainly isn’t the case within the industry itself. News of impending climate disaster has been around for at least 4 decades already. There already exists a vast body of knowledge that has been built-up aimed at reducing industry’s reliance on fossil fuels along with a bag of other serious environmental concerns.  It’s not hard then to find that non-governmental standards and initiatives exist outside of the ‘Westminster Bubble’  in pockets of construction where there operates a more aggressive call for sustainability.

Distilling key points for reducing carbon of both ‘operational’ and ‘embodied’ isn’t always easy, but a few points can be made as significant ‘takeaways’:

Tips and pointers for reducing embodied carbon in your construction projects:

Fabric first approach:

Put simply, ‘let the building shell do the work’ allowing the structure, or fabric, to mitigate or massively reduce energy demand is the most efficient way to build after all the most carbon friendly energy is energy that is not used. Try to use materials that have low embodied carbon. Natural products, timber, wool, straw, hemp etc. act as a carbon store and are often manufactured using a low or renewable energy source. Some natural materials can be carbon negative (some would say positive) in that they sequester more carbon than their production emits. 

Think long term:

Optimising the life cycle impacts for anything less than a 60-year span is not worthwhile. The building fabric is prone to decay if the structure becomes damp. The management and control of moisture in buildings is critical to their longevity. Consider breathability for both new and existing buildings, especially timber, and monolithic construction. Natural materials are breathable and offer a good solution to dealing with moisture. This is particularly important in older buildings, because they were designed to be open to absorbing and releasing moisture.

Build in flexibility.

This may be addressed by creating a building that is either highly adaptable or with elements that can be reconfigured or reused. There are many interesting ways of using natural materials whereby the building can be flexible. For example, super strong flax based partition systems (such as the Faay partition wall system) located using timber tracks can be relocated and re-used as can using timber joints that do not utilise glue or nails (e.g. Brettstapel), therefore allowing the parts to be taken apart in future.

Include cost and not just price.

When assessing the cost of a material it is wise to include how the product is procured, installed (it may save time or eliminate the need for another product), its performance benefits and consequential savings such as reduced wastage or maintenance in other words it is a form of value judgement. Price is what you pay. Cheap now can be expensive later as you need to replace or repair more frequently, adding to your operational costs. Every time you replace or refurbish a material, you add carbon emissions to your building account.

Use multi-functional elements.

Increase the contribution of each element so that others can be removed. Avoid elements with limited value, e.g., ensure your internal layer can provide racking, airtightness and vapour control, or your insulation provides performance beyond minimum regulation U-values by offering other performance benefits such as vapour management or heat transfer delay, ensure that internal ceilings can provide acoustic, thermal and fire protection. For example, timber and straw modular systems can offer structure as well as excellent acoustic and thermal insulation.

Choose long-lived solutions for windows and roofing.

Investing in durable materials means fewer replacements over time, which means fewer carbon emissions, less waste generated, lower life-cycle costs and less tenant disruption. What is a durable and suitable material for your market varies depending on the conditions, however, the principle remains the same.

Value LCAs and EPDs.

Materials are a very important part of a building’s impact. A Life Cycle Assessment (LCA) assesses the environmental impacts of a specific material or product. This often takes the form of Environmental Product Declarations or EPDs and it basically means calculating the LCA of a product, from the extraction of the material through manufacture, use, replace or repair to disposal and recycling.

Building materials already contain embodied impacts when they are purchased and brought to the building site. Their production has caused certain gases to be released into the atmosphere, the transportation of the materials to the manufacturing facilities has caused other impacts, and so on. If an EPD of that material is available, it means that the lifetime impacts of the material have already been calculated and declared, and that makes it easier to calculate the environmental impacts of the building.

Diagram showing the life cycle of construction materials, the CO2 arrows indicate the predominant effect on carbon contributions.


Reducing the amount of carbon generated by the fossil fuels we burn to operate our buildings is crucial, but it should go hand in hand with reducing embodied carbon. After all, while operational emissions can be reduced over time with building energy efficiency renovations and the use of renewable energy, embodied carbon emissions are locked in place as soon as a building is built or refurbished.  Increasing our use of natural materials will sequester carbon already released into the atmosphere, lower the carbon that is produced in material manufacture, and has the potential to optimise building lifespan in order to decrease the frequency of demolition and replacement. Each individual, whether they be a homeowner, specifier, investor or construction professional, has the agency to make decisions to decrease embodied carbon. It is our responsibility; we have to act now.

About the authors: this article was written by ‘Ecomerchant’ and the ‘Architects Climate Action Network’ (ACAN) in response to our invitation to have their say in the conversation around embodied carbon and how to take action to reduce it.

Ecomerchant are an independent, employee-owned builder’s merchant supplying sustainable and natural building materials. Ecomerchant focus on ethically sourced, sustainable building materials and a fabric first approach to building. The environmental merits of every product are considered with Ecomerchant opting not to sell products which cause excessive environmental impact. The carbon footprint of materials is a critical component of this assessment where low carbon alternatives will always be preferred. Ecomerchant are active members of ACAN.

Take Action:  www.ecomerchant.co.uk

The Architects Climate Action Network (ACAN) is a network of individuals within architecture and related built environment professions taking action to address the twin crises of climate and ecological breakdown. The collective has three overarching aims:

  1. Decarbonise now!
  2. Ecological regeneration!
  3. Cultural transformation!

Take Actionhttps://www.architectscan.org

Additional resources:

RICS Professional standard on Whole life carbon assessment

LETI Embodied Carbon Primer 

RIBA 2030 Climate Challenge Plan 

Inventory of Carbon and Energy 

The UK’s Passivhaus Trust on EnerPHit And Retrofit

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