Based on our own observations from G&T’s involvement in numerous low carbon schemes, there are an increasing number of alternatives to traditional materials like cement and concrete. For example, blended cements and concretes that store carbon and are made from entirely different materials such as wood, hempcrete, straw bales and mycelium. To reach the interim carbon targets set by bodies like the RIBA, we need to use:

  • Natural products (or those with low energy manufacturing processes) – eg materials with natural fibres that come from renewable sources and require little processing such as timber
  • Materials with recycled content – this lowers the need to extract virgin/raw materials for initial processing
  • Reuse materials – reusing materials that still have a service life is another way to reduce new material extraction. The impacts of dismantling those materials and making them fit for reuse can be lower than creating new materials

Currently, low carbon materials can have a capital cost premium. However, a growing range of alternative, low carbon building materials is becoming available. The expectation is that as product suppliers become more environmentally focused and take further steps to improve their own carbon credentials, they will get better at proving their low carbon provenance – making it easier for new buildings to achieve the aspirational embodied and operational net zero carbon targets. Furthermore, once commercialised on a greater scale and uptake increases in the UK, prices for these alternative materials may well fall in the long-term[1]. However, it’s important to note that for low carbon material prices to fall significantly, growing demand will need to be accompanied by a greater number of suppliers providing a wider range of sustainable materials.

It will also be important to encourage design teams to focus on reducing carbon through informed decision making. A greater focus on the issue at the design stage will drive the supply chain to improve processes and reporting, making it possible to achieve significant improvements to the embodied carbon in our buildings without additional cost.

The UK has experienced a slow uptake of low carbon materials. Stakeholders are often cautious about using novel materials, perceiving them as higher risk, higher cost and more difficult to use. The product has to ensure safety over decades and many of these materials are unproven over this length of time. There are also concerns over whether there is an adequate understanding regarding the application of these products as well as financial, insurance and legal constraints.

However, using low carbon materials is only part of the solution. The embodied carbon of a building element includes its material footprint and the waste that is generated during its construction. In this respect, fully embracing modular construction and prefabrication under a controlled environment will enable a reduction in waste and associated carbon emissions.

We also need consider the lifecycle of the materials. Internal spaces are reconfigured frequently and the aggregated impact of replacing internal elements multiple times during a building’s lifecycle has a significant impact on carbon emissions. As such, it’s important that finishes include low carbon materials that can either be recycled or reused. Otherwise, every time you replace internal elements, you add carbon emissions to your building account. Designing for disassembly (ie enabling sections to be easily taken apart) will allow for a more efficient recovery of materials that are being replaced, preserving the value of the material as well as reducing overall waste and carbon emissions.

Schemes that allow you to lease air-conditioning equipment, lighting systems, finishes and even furniture already exist and are commonly utilised. They enable a circular economy approach where components are constantly replaced with newer, more efficient ones and older ones are reused. Recent pilot projects[2] across Europe have attempted to extend this business model to façades, where they can be leased through long-term service contracts. Making façade systems that can be recovered and re-purposed (instead of the current ‘take, make and dispose’ model) means they can be leased to building owners/managers and integrated into older, less energy efficient buildings. This can improve energy performance of existing stock, make cost savings on energy consumption and reduce carbon emissions – all without having the upfront capital.

With the façade suppliers assuming responsibility for maintenance and upgrades, they are incentivised to keep them as up-to-date and energy efficient as possible. This prevents depreciation, encourages reuse and material recycling and helps to de-materialise the construction industry.

How design and procurement processes might need to be adjusted to bring focus to the issue of carbon:

According to G&T’s sustainability consultant Richard Francis there needs to be a focus on both construction and operational carbon, so that whatever is done to reduce embodied carbon at the design stage must also enable better operational carbon over the lifetime of the project.

Richard explained that we are seeing, and will continue to see, the use of new materials and newer uses for materials (timber is a good example), plus an “upping of the game” in terms of recycled content for aluminium, steel and concrete. Lighter, lower buildings, with reduced substructures are a potential way forward as substructure and superstructure account for 75% of embodied carbon emissions.

Richard also noted that modular and Design for Manufacture and Assembly (DfMA) construction techniques will gain more ascendancy in the coming years and that this will help reduce both operational and embodied carbon. Modular and DfMA techniques change how we approach the design stage and allow us to design out waste at each stage of the project lifecycle and set standards on resource and energy use.

Richard suggested that we’re likely to see leaner design and procurement processes with fewer, more natural and robust materials being used that reduce the need for more frequent fit-outs. However, when existing buildings are refurbished we’re likely to see greater reuse of the materials/structure. Finally, Richard also expects to see more naturally ventilated and mixed mode buildings, along with smarter buildings that can better control energy use and reduce operational carbon emissions.

How to encourage the supply chain and procurement teams to embrace the new low carbon agenda:

Companies such as G&T are in advantageous position to provide clarity on the cost and availability of low carbon materials, as well as design options, and can therefore encourage the adoption of low carbon technologies and processes on construction projects. There are a number of ways we are doing this which include:

  • Running carbon budgets alongside cost plans – we are doing this now and it is the thinking behind the Parametric And Numeric Design Assessment (PANDA) tool that we are developing with the University of Cambridge and Price & Myers. The software can save up to 40% of embodied carbon on new build construction. Find out more here.
  • Sharing lessons – we are working on projects that involve all the major NZC frameworks – WorldGBC, LETI, UKGBC and RIBA so we understand the different pinch points, along with the costs of the various approaches.
  • Finding creative ways to think about materials that help the NZC agenda – this is the point of our recent Mass Timber Forum series in which G&T hosted expert panellists that discussed the benefits and challenges of mass timber solutions and how we can encourage widespread adoption of the material and forward the NZC agenda.
  • By being involved in pioneering projects - G&T is in a unique position to align forward-thinking clients with suppliers who are able to offer services that help them meet company NZC commitments.

How simply focussing on embodied carbon as a key design driver is already moving the dial:

Embodied carbon represents 50% of whole life carbon on new buildings[3] – so 50% of carbon “used in the project” occurs before the tenants even move in. Therefore the shift of focus to embodied carbon is a fundamental step to meeting the various carbon reduction targets such as the RIBA 2030 Climate Challenge for Net Zero Buildings.

Because embodied carbon is now part of policy (eg the GLA’s draft Whole Life-Cycle Carbon Assessment guidance and template) and expectations (UKGBC Framework) there is no longer the assumption that NZC applies only to operational carbon – this is hugely important. For a new building to be considered NZC it has to address embodied carbon.

Carbon targets now require developers and landlords to “own” the issue, both at the construction stage (embodied) but also during operation (due to energy use intensity targets). Developers can no longer pass the carbon question/issue onto tenants and so are increasingly measuring embodied carbon using impact modelling tools and carbon calculators to inform the design process and reduce emissions.

The recent focus on embodied carbon has encouraged the industry to collaborate more closely to tackle the emissions issue. For example, companies from across the architecture, engineering and construction industries have created a free digital embodied carbon calculator called ‘EC3’, enabling easy comparison between potential building materials so that more sustainable options can be chosen. The open-access tool, which is based on a digitised database of US and Canadian Environmental Product Declarations of more than 16,000 materials, will help accelerate low embodied carbon design and help cut emissions originating from the manufacture, transport and installation of construction materials. In fact, during its pilot period, participating projects were able to reduce their embodied carbon emissions by 30% without significant financial impact.[4]

How the BCO (and agents) might need to reconsider their requirements for offices to align tenant provisions to a low carbon world:

Agents need to be aware that tenants have net zero carbon commitments of their own. Finding energy efficient, low carbon (in operation) buildings is becoming a top priority for tenants who have carbon commitments and reporting requirements.

Richard Francis believes that whole building energy disclosure is the way forward in many parts of the world and things like NABERS UK (a system for rating the energy efficiency of office buildings) are increasingly driving us in this direction. We expect that disclosure of energy performance in office buildings will become much more common and tenants will have much more detailed knowledge about how spaces actually work, resulting in less guesswork around whether a building performs or not. Forward-thinking landlords looking to provide an energy efficient space can and will be expected to lead with this.

Historically, BCO standards required “overbuilt” and tightly constrained requirements to be met with regard to building performance. This meant that buildings working to the BCO standards tended, on average, to encourage more embodied and operational carbon. Currently, the BCO 2019 key criteria which forms part of the BCO Guide to Specification does not set specific standards for embodied carbon, other than indirectly referencing BREEAM as a sustainability benchmark. However, the BCO Guide does include an appendix that provides practical solutions aimed at achieving low and zero carbon installations across a range of building services elements. The BCO is actively looking to unpick the challenges around embodied carbon and so we may see a loosening of the standards as clients negotiate the NZC terrain.




[4] https://www.constructionglobal...