Reducing carbon in public sector projects, an interview with Conall Boland

Can you explain some of the greenhouse gas emissions associated with cement and concrete use?

The main source of embodied carbon in concrete is the cement – the material that binds the sand and aggregate together to form concrete. Making cement is an energy intensive process. It involves heating limestone to very high temperatures and when the limestone breaks down in that heat, it also emits carbon dioxide. So there are emissions from the energy use and from the production process. One of our key goals is to reduce the amount of traditional cement in a concrete mix.

What is the difference between embodied and operational carbon?

Embodied carbon is mostly in the materials and the construction process for a building. It can also come from a refurbishment. Let's say you took out windows after 20 years and replaced them – that also counts as embodied carbon. But for the most part, decisions taken at the design stage are the most important, particularly selection of materials. If you get in early in the project pipeline during the design stage and build good practice into the design, it helps out a lot down the road.

Operational carbon is more familiar – it relates to the energy use over the building lifetime for heating, power and appliances.

How are the government and public sector bodies encouraging this change in our approach to procurement and design?

At the moment, the government’s approach is to encourage best practice and to improve knowledge and understanding about cement and concrete procurement, and to encourage the design teams employed by public bodies to be much more efficient and careful about specifying cement and concrete. In the longer term, it's possible that the government will make it mandatory or add some regulatory requirements on specific carbon levels. The next few years will be about encouraging best practice and better design.

How can structural engineers embed lower carbon approaches in their projects?

When you train as a structural engineer, your first priority is that it's safe, that the building or structure is stable and durable. But that can still be done with lower carbon approaches. We're not asking to compromise on safety or durability, but we're asking people to move away from business as usual and to try and achieve the same stability and safety by using lower carbon approaches. There is an element of relearning and upskilling to achieve that.  Plus, the architect needs to be working in the same direction.

Why is rapid hardening cement more carbon intensive?

So that’s ‘CEM I’ cement. It's not so much rapid hardening, but it's a pure form of cement that is almost 100% clinker from the cement factory. If you went back 30-40 years or more, that would have been the main component when you purchase cement. But over recent decades, we've realised that you can mix other materials in to make a range of cements, such as CEM II or CEM III, and you can still retain the strength and durability performance. At this stage, CEM II cements have similar strengths and setting and technical characteristics, but they have about 10-15% less carbon. What we're saying is that the default for public projects should be to steer clear of CEM I unless there's a very particular reason to use it.

Could you give an example of when you might need to use CEM I cement?

There can be circumstances, for example, if you had a very corrosive environment or you had an environment where durability is tantamount. Maybe exposure to things like acids, or in applications where there is a risk of corrosion.

How can we incentivise designers and contractors to reduce the carbon footprint of their projects?

Well, if we look at it today, we already have construction contracts where there's incentives for reducing the cost. You can also have incentives for reducing the programme. In both cases, you're able to measure the benefits. You provide an improved performance against the baseline, and it gets you a financial reward, so as a contractor, you're encouraged to innovate and to find good solutions.

As for carbon – it's the same thing, you need to be able to quantify what the business as usual expectation is. You need to ensure that there’s a system measuring that, and then you build in a reward for the contractor or the team to result in a project that has a lower carbon footprint. It's relatively early days for that, but there are already projects that we're working on. For example, the A66 highway project in the UK, where there's an overall 30% carbon reduction target for all project teams, and there's a built-in reward in the contract if that target is exceeded.

Is there a risk these methods could increase construction costs or slow down project delivery?

We worked closely with EY in this study and we examined the global supply chains for key materials, including alternative binders. While there will be limitations in the future, currently the main replacement in Ireland for cement is GGBS, and that seems to have a reasonably solid supply chain. At the moment, costs are similar to the cost of ordinary Portland cement, so there’s some reassurance there.

In terms of affecting programme or cost, the transition to lower carbon construction is going to create some turbulence. We'll be using new materials we have to familiarise ourselves with, and there may be a period where it takes time to scale those up and they may start off being more expensive, so it's hard to guarantee that there will be no impact on cost or programme.

What we're recommending is a transition, so there are short-term measures that can be taken now with relatively little impact, but we do need to start researching and finding alternative cement materials in particular, and we need to be prepared to innovate, run pilot schemes and develop familiarity with those materials, and the public sector needs to be involved in that.

What does the PAS 2080 carbon management approach entail?

PAS 2080 puts an emphasis on measurement and developing reliable data for your project’s carbon content. It also puts an emphasis on carbon reduction, collaboration and good reporting systems, so that it's quite clear what savings you've made and what benefits you've brought through applying PAS 2080. It’s a good model and we're increasingly implementing the principles of that in projects for our clients.

How do you measure the carbon impact of our projects?

PAS 2080 requires measurement and if you want to find this measurement, you use a carbon assessment tool. There are free tools. There are tools provided by the Institute of Structural Engineers or Transport Infrastructure Ireland. You can also get software like One Click LCA (life-cycle assessment), which is what we use.

For any of those, if you have the data, they'll help you convert your construction process into an associated carbon impact. But you do need the data and you need to know what materials you're using. You also need to know what kind of construction methods you used. If you've got equipment on site, how many hours is it running? What kind of consumption of fuel? What kind of consumption of electricity? What kind of transport impacts?

So all of that is brought together in a structured format and then you can report it. Ultimately, if you’re building something as simple as a bungalow, you want to see where the carbon hotspots are. The concept is you then go back to those and say, what are my alternatives?

If you could click your fingers and change one thing about the whole process, what would it be?

If I could click my fingers, I'd make it mandatory for every structural designer to have a qualification in low carbon construction, and that all public bodies would only employ people that have that formal qualification. I think that would make a difference, to create a cadre of designers so that we're competing not just on cost, but that we also create a competitive attitude to carbon reduction and a real ambition in that sector. We have some great designers, but we probably need more of them.