3 ways to cut carbon in construction, including a competition

Posted by Derek Mason

8th November 2022

Picture credit: Robina Weermeijer on Unsplash

A new facility for people with neurological disorders is set to be ground breaking both in the work that goes on there, and the multifaceted approach to cutting carbon and waste during construction of the new building.

The University College London Institute of Neurology & Dementia Research will open in 2024 on Grays Inn Road, on the site formerly occupied by the Royal Free Hospital and then the Royal National Throat, Nose and Ear Hospital and the Eastman Dental Hospital.

As well as being a research centre for UCL, the state-of-art facilities will be headquarters of the UK Dementia Research Institute and the UCLH National Hospital for Neurology and Neurosurgery – the UK’s largest dedicated neurological and neurosurgical hospital.

The state-of-the-art 17,500m2 facilities will be home to three bodies: the world-leading UCL Queen Square Institute of Neurology; the headquarters of the UK Dementia Research Institute, which is the single biggest investment the UK has ever made in dementia; and the UCLH National Hospital for Neurology and Neurosurgery (NHNN), which is the UK’s largest dedicated neurological and neurosurgical hospital.

The £180m facility includes part of the existing hospital building, built in 1895, which will be linked to the new building via bridges. The new facility will be four storeys above ground plus three basement levels.

There is some controversy over the demolition of part of the existing hospital, which resulted in the loss of a historic Victorian courtyard, leaving only the front section of the original building. As well as the demolition not being in keeping with net-zero-carbon targets, it was questioned by local groups and Historic England, who argued the building and courtyard should have been preserved.

With building work already underway, this is a moot point in this case, but it’s a subject that will come up again and again. As hitting carbon targets becomes more urgent, demolition will need to be avoided. In this case it was found that ‘public benefit’ outweighed ‘heritage harm’.

Cutting carbon in construction

For the construction element of this project, concrete is a major element, so reducing its volume was key to cutting carbon. But concrete was not the only focus of the project. The team also looked at on-site fuel usage during the demolition and build and considered the circular economy.

Concrete volume reduction

The volume of concrete used has been reduced by using arches instead of flat slabs in between the concrete beams at the front of the building on levels one, two and three.

Additional reductions were achieved by switching from secant piles to contiguous piles for basement walls. Contiguous piles are reinforced, with a small gap between them, whereas secant piled walls use overlapping unreinforced piles with secondary reinforced piles. This switch saved approximately 1000 cubic metres of concrete and approximately 150 tonnes of CO2e.

Low carbon concrete

The team also aimed to use lower carbon concrete by using cement substitutes including Ground Granulated Blast furnace Slag (GGBS). As you may already know, this is a fine powder produced in iron and steel-making processes that can be used to replace a significant percentage of the cement in concrete. The percentage added depends on the usage and strength requirements. Overall, this approach reduced carbon by around 15%, compared with standard concrete.

Fuel reduction

Reducing fuel consumption by cutting idling time seems like an easy win, but is not always easy to achieve when habits such as leaving vehicles idling are ingrained. So, the project team introduced a fuel saving tournament as an innovative way to cut fossil fuel usage. With rewards offered to those who cut idling the most, this cut idling time by 50%.


With 700 tonnes of steelwork for temporary works, circularity was also a focus. Twenty percent of the steelwork was repurposed from other projects and 70% of the new steelwork is set to be reused in future builds. Part of the demolition was also crushed and reused on site, saving 4,300m3 of aggregate.

This project demonstrates that while the industry has a long way to go in terms of reducing impact, attention is being paid to carbon targets. Carbon that is being cut largely fall in areas where there’s an economic benefit too, which is what we would all expect to see.

Meanwhile, if I can offer you assistance with the structural elements of an upcoming project, please do get in touch.

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