March 2022

Angela Pllu, Environment & Sustainability Manager
Angela Pllu, Environment & Sustainability Manager

Advanced Works onsite have come to a close. As we work with the customer on the next phase, we’re focussing on minor works with a limited onsite presence, but work behind the scenes continues as we consider some of the knotty issues relating to significantly reducing the carbon emissions from this scheme.

Does Zero Carbon Cost more?

Understanding the financial costs associated with zero carbon construction is a critical element of being able to deliver it. On this scheme, one of our aims is to analyse and capture this in greater detail.  

At the moment, and until this way of building becomes the norm, the upfront costs of lower carbon options are certainly higher, although in most cases, the costs are recouped over the longer term as lower carbon options can be more energy efficient for example, thus saving on energy costs. The aim of this project is to trial as many low carbon options as we can, without any additional cost to the customer. Once we’ve trialled them, we want to be able to replicate the best solutions across our other sites.

Our approach to delivering this at no additional cost has three key elements:

  • Working collaboratively with our existing supply chain partners to bring them into this trial. For example, working with Sunbelt rentals who are subsiding the cost of the eco-friendly cabins we are using at this site to allow us to collect the best data on their performance and showcase the benefit these eco cabins can really deliver.
  • We are working with a number of third parties to obtain funding for some of the more innovative trails and working methods we would like to trial. An example is a project with Zero Waste Scotland which looks at the barriers our supply chain face in bringing sustainable solutions to our projects and how we can help accelerate their own climate action programmes through collaborative working environments. We will use a third-party expert to chair collaborative working groups with our supply chain to look at the barriers and bring the right players to the table to discuss how we can overcome them and implement them on our projects. One topic we hope to examine is the potential to move to a model of ‘servitisation’ for our customers – where, rather than buying the new items, they rent them from the supplier who also maintain the item. This generally means assets will remain in use for longer, making it easier for manufacturers to implement closed loop recycling systems for their manufacturing process.
  • Working actively with partners who already have funding in place for trialling new innovations. Since 2018, we’ve been working with Roisin Hyde, a Fulbright award-winning Architect and Doctoral Research Student at Queen’s University Belfast in the area of Novel Materials, Architecture and Design (NoMAD), on her geopolymer concrete. This is a low-carbon concrete substitute made from up to 96% waste materials from mining, quarrying, metallurgy, water purification, incineration and agriculture. We are now looking at how we can bring Geopolymer concrete into use on a commercial scale on our projects. Finding new, low carbon alternatives to traditional concrete is critical to decarbonising the built environment.

One of the common themes in this diary entry is the need for collaboration with innovators, the supply chain, academia and funders. It’s something Balfour Beatty prides itself on. Collaboration is key to a sustainable future and we are keen to hear from anyone who thinks they could collaborate with us on this project, or others, to deliver a more sustainable future.

Something that is likely to play a key role in making lower carbon options more cost-competitive, is the rising cost of the materials we traditionally use. For example, in April 2022, the rebate on red diesel ends meaning that the cost of powering our diesel plant will significantly increase. This price increase makes hydrogen fuel more cost competitive for our sites than ever before and we are actively planning our hydrogen route map.

Energy and fuel price increases, teamed with shortages in certain products (including Ground Granulated Blast-furnace Slag, bitumen, fuel, utilities, timber, plastic, steel and cement-based products) are also driving significant price increases for many traditional materials and are beginning to make lower carbon options comparatively more affordable, although this is something that is continually changing and evolving. If this is the case, it is likely to accelerate take-up and trialling of these lower carbon options which, in turn, should drive the cost of them down as they become more mainstream.

Surplus topsoil

The work we are doing on this site will generate a large amount of topsoil which is of very high quality. As the name suggests, topsoil is the upper layer of soil, up to around 10 inches. It is usually nutrient-rich, fertile, and excellent for growing plants and vegetables. It takes around 100 years to make an inch of topsoil and as such it is a valuable and finite resource. The Royal Botanic Garden Edinburgh will reuse much of this displaced topsoil, benefiting other areas of the 70-acre Garden. However, there will be some surplus soil which cannot be reused within the Garden or accommodated in the design.

We always try to reuse topsoil on our sites. Where this isn’t possible, it would normally go offsite to be reused elsewhere. We typically look for other sites that need topsoil for their own developments or supply chain partners that can retain the soil and then sell on when others need it. Where this is not possible, our final option is to take the topsoil offsite for use as landfill cover, to restore landfill cells.

Trying to think creatively with the customer about how this could be used more sustainably in the local area, we offered the soil to local individuals and organisations and were delighted to be inundated with requests from the community, including schools, community groups and others. We have had requests for some 50 tonnes to be delivered around the local area for reuse, which we are in the process of distributing. We are able to do this as the Scottish Environment Protection Agency (SEPA) have agreed we can use the Greenfield soils protocol meaning we can work with the material as a clean material and not a waste. The reuse of waste at another location is heavily regulated, something which acts as one of the current barriers to circularity within the construction industry.

Green skills

Having a construction workforce that is trained and ready to deliver net zero is essential to getting there. We need to invest now, because we know we will need them increasingly. This includes a whole range of skills such as low carbon construction, understanding the sourcing of materials and embodied carbon, digital skills, life cycle assessment/costing, carbon and water footprinting and designing in a way that takes into account both embodied and operational carbon and resilience to climate change. Given the urgency associated with climate change and decarbonisation, updating and refocusing people’s existing skills to ensure that they are fit for purpose is fast becoming a priority, as is creating a pipeline of people coming into the industry who have some of the new skills we’ll increasingly need.

We’re undertaking a Gap Analysis mapping the existing skillsets of our workforce against the skills we are increasingly seeing a need for. Work we’re doing in support of this includes:

  • While not everyone needs to be a sustainability expert, it’s really important that everyone has a basic level of carbon literacy and an understanding of the language and concepts being used. To that end, we‘ve launched a UK-wide Carbon Concious education programme to ensure that all of our workforce understands the carbon costs of their behaviour and how they can play their part in helping Balfour Beatty reduce its carbon footprint – as well as reducing the carbon impact of their own activities.
  • The construction supply chain is responsible for 80% of the sector’s emissions. Our supply chain partners have a vital role to play in helping Balfour Beatty meet its own decarbonisation targets as well as those of our customers. For example, through collaboration with our supply chain partners, Balfour Beatty’s aim is that all of the products and materials we procure will be net zero carbon by 2040. In 2021, Balfour Beatty partnered with the Supply Chain Sustainability School to survey 40,000 companies in the construction supply chain to help us understand the support they need to decarbonise their operations. One of the key barriers highlighted in the subsequent report Greening the Chainis the skills gap, and a lack of training available to plug that gap. As a result, we are rolling out carbon literacy training not only to our own staff, but to our supply chain as of March 2022. Carbon literacy training is part of the Carbon Literacy Project by the Carbon Literacy Trust. You can find out more about it here.
  • Working with partners to ensure that qualifications and training frameworks reflect the importance of carbon-related knowledge and skills, helping to increase the level of understanding of climate change and how their skills contribute to net zero, for example, by ensuring that sustainability is included in all apprenticeships.
  • We are recruiting people adept in a wide range of digital skills which will enable us to fully embed BIM and use digital tools to help us calculate the potential carbon impact of infrastructure and allow us to trial different options in a digital space first, to maximise efficiency and minimise carbon emissions.

One of the elements of this scheme in particular which relates to new green skills is the installation and operation of the ground source heat pumps for the district heating system.

The first phase of the scheme involves the creation of a new, efficient energy centre to replace existing facilities at the Nursery to the north of the main Garden. The new energy centre will introduce ground source heat pumps which, coupled with new low heat loss pipework, will result in a 17% reduction across the whole of the Royal Botanic Garden, Edinburgh.

Balfour Beatty has experience in delivering this type of technology, not least at the Caird Park Low Carbon District Energy Hub – a hybrid ground source heat pump, powered by a mix of renewables which supplies a district heating network to warm a large proportion of Dundee’s social housing, for which Balfour Beatty, Dundee City Council and ESB won the Carbon Reduction Award at the Scottish Green Energy Awards in 2019. However, the technology is still relatively new and involves a number of complex design considerations. There is therefore currently only a limited supply chain that is able to deliver these types of systems and to service them following installation. In practical terms, this means that we are working hard to source those who are already able to deliver this, and taking active steps to make sure our supply chain partners are ready and that we are able to capture and replicate this knowledge in our own workforce. We are also looking ahead to the handover stage to ensure a soft landing for the customer and that they have everything they need to operate and service the system in the future.

Key learning

Our action

On cost for zero carbon construction sites we are in a period of transition as we move away from red diesel. As the technology solutions become more readily available we will see a series of changes i.e. the move to battery powered tools. To ensure these transitions can be delivered at zero cost, we need to look at the whole cost not just the red diesel cost but its transportation / refuelling / containment etc. If we have a mains connection the charging infrastructure can be installed and the costs shared across the supply chain for charging.

Learning shared with the Sustainability and Procurement teams and filtered back to the rest of the business.


Topsoil is a precious resource and every effort should be made to reuse 100% of it. We have c.50 tonnes of soil allocated to local allotments and schools charitable initiatives as SEPA have agreed we can use the Greenfield soils protocol, meaning we can work with the material as a clean material and not a waste. We need to continue to collaborate with other UK regulators so that this valuable resource is classified as a material that can be reused and its inherent value is not lost by being classified as a waste.

We are highlighting the approach we and SEPA have taken on this site to the UK Government and suggesting that they consider reclassification of topsoil.

In order to secure sufficient people with the skillsets we need to undertake zero carbon construction, we need to work more closely with academia, CITB, the Supply Chain Sustainability School, Construction Scotland and others, to work out how we best future proof the future construction industry and help upskill the whole sector.

Learning filtered back to the rest of the business, specifically Group HR.

Where one part of the business and our supply chain partners work on an innovative, sustainable solution, we need to ensure that we are capturing and sharing the learnings and skills as widely as possible to ensure that we are able to deliver these solutions efficiently for all our customers and that handover to the customer is as seamless as possible.

Learning filtered back to the rest of the business, specifically the Sustainability team.

If you have observations or queries on the points outlined in this entry, please contact: