Read about the AT Schüco showroom panel discussion that explored how we balance the carbon cost of demolition, conservation and building performance.

Embodied carbon is at the heart of the sustainability conversation and how we use our current building stock will be the key to ensuring a viable sustainable future. At this Schüco Showroom panel discussion, we explored how we reconcile the need for energy-efficient buildings against the carbon cost of demolition and construction, as well as how we find the right balance between conservation and building performance.

The event kicked off with four presenters: Angie Jim Osman, a director at Allies and Morrison; Darren Price, a director at ADAM Architecture; Gita Maruthayanar, an associate director at Atelier Ten and Julia Yao, sustainability lead at PLP Architecture, doing quick presentations outlining a stance on the subject, backed up with case studies. Afterwards, the four sat down with BBC Environmental Analyst, Roger Harrabin and AT Editor and panel Chair, Isabel Allen, to discuss and explore the positions further.

Speakers (clockwise from top left:) Panel Chair, Isabel Allen; Roger Harrabin; Angie Jim Osman; Darren Price; Gita Maruthayanar; and Julia Yao

First, Angie Jim Osman looked to Kings Cross, London where her practice has been working in, highlighting the German Gymnasium — a place that has occupied the area since the 19th Century and is now a restaurant showcasing German cuisine. Beyond retention of the built fabric and the embodied carbon with it, Osman noted how retaining the building also worked at an urban level, through careful master planning and urban design, which means it now also activates a key public square outside Kings Cross Station.

Inside the refurbished German Gymnasium (Courtesy: Allies and Morrison)

Also on the Kings Cross site, Osman pointed out, is the ‘Capella’ residence, a housing scheme from Allies and Morrison that is set to deliver 176 new homes. The building is designed to use 100 percent renewable energy through green gas and electricity. Access to light and green space, in line with Well Guidance, is also achieved, something that Osman postulated would not be possible with an older building, particularly given that derelict sheds previously occupied the site.

However, Osman was also aware that even new builds must be flexible to last long. “We have a duty to ensure that buildings do not become prematurely obsolete,” she said. “Protecting these assets and assessing to see if they are resilient to future change is incredibly important.”

Next was Darren Price, who set the scene with a few facts about the state of the UK’s building stock. “The UK has the oldest building stock in Europe, with approximately 26 million buildings,” he said. “1.2 million of those are in conservation areas and more than 400,000 are listed.”

These, said Price, can’t simply be replaced and, according to him, 70-80 percent of this building stock will still be with us in 2050. So how can we bring them up to speed? He used a Grade II* Listed manor house in the Cotswolds that dates back to the 15th Century as an example of how to do this, furthering adaptability for renewables and a change in energy supply.

Retrofit works being carried out on-site on the Cotswolds property. (Courtesy: ADAM Architecture)

Here, a ’fabric first’ approach was employed, which included major repairs, removal of asbestos and layout changes. Vast research had to be carried out for this, understanding how the building came into being, while also being able to understand what elements of the building fabric weren’t performing, such as a floor slab that was causing damp throughout the property. This was replaced with a more sensitive, breathable structure and new underfloor heating, while the original surface slabs were relayed so any visual character was not lost.

Following Price was Gita Maruthayanar, who noted the UK Green Building Council’s (UKGBC) target trajectory for operational energy efficiency for commercial offices — which can be applied to the property sector, said Maruthayanar — to be net-zero carbon by 2050, for which we need to reduce operational energy use by 60 percent.

Maruthayanar highlighted how reusing construction materials is key to reducing a building’s carbon footprint along with retaining the grid superstructure. “The grid size matters,” said Maruthayanar, who added that a six-by-six timber frame will have less embodied carbon than a reinforced concrete frame with a post-tensioned slab more almost twice its size.

Knowledge on building construction and access to detail drawings of a building was also noted by Maruthayanar, particularly with regards to façades. The latter are a key component of the building fabric and are often the largest denominator of thermal performance. How these are detailed, with this information being readily accessible, is key to structures being able to last much longer, giving those that may conduct a retrofit later on the detailed design and information on how that façade is constructed and operates.

Diagram showing a building’s MEP’s embodied carbon footprint compares with other building components. (Courtesy: Atelier Ten)

Another “area to target” for reducing embodied carbon loss noted was MEP, with Maruthayanar pointing out that piping and ductwork and cables and containment make up 44 percent a building’s MEP — “a key carbon hotspot” according to the associate director.

The final presentation came from Julia Yao, sustainability lead at PLP Architecture, who put the example of Corso Como Place in Milan for which PLP carried out a renovation to an existing tower. Retained the sub- and super-structure, the building’s façade was replaced with glass, improving its thermal and daylighting capabilities.

Rendering of the Corso Como Place in Milan. (Courtesy: PLP Architecture)

Another example from Yao was Cleveland Clinic in London for which the opposite strategy was adopted. Partly due to being located in a conservation area, the building’s 1950s neo-classical façade was retained. Refurbishment in the 1990s had seen the building be turned into offices, however, this had also resulted in a misalignment between the façade and slab. This was fixed with further insulation being added to the façade to aid the building’s performance.

Yao’s final example was a project spanning the Holborn Viaduct in London and which consolidated three buildings already on site, resulting in their removal. “This was one of the first buildings that went through the whole life carbon assessment through the planning policies,” said Yao.

The carbon calculations that resulted from such analysis indicated that a new build was essentially on par with refurbishment — leading PLP to make a qualitative judgement that a new office would enrich the city more than what pre-existed.

The panel discussion in full swing. (Courtesy AT)

Following the presentations, the panellists sat down with Chair Isabel Allen and Roger Harrabin.

“The conversation going on here and indeed in architectural circles and magazines is way far advanced compared to what it is in the public,” commented Harrabin. “The public still, really, has no idea about this.”

“I have tried to make embodied carbon into something visual, because ‘TV people’ don’t like stories that don’t have pictures,” he continued, going on to add how, with the Eden Project, he has commissioned five sculptures in the five main embodied carbon materials: steel, cement, aluminium, paper and card, and plastics — due to be featured on Newsnight soon.

Following questions from the audience, the subject of building lifespans arose. Should we be designing buildings that last much longer into the future?

“I am personally appalled that architects, and perhaps developers more so, produce buildings that are going to come down in 40 years, it’s scandalous,” Harrabin responded. “The Victorians were able to build mass housing that lasts until today, yet we can’t. The economics behind buildings built to last 40 years are clearly not right.”

In the closing remarks, Harrabin also spoke on the impact the panel discussion had on him. “I have completely flipped from my original thought that we should knock buildings down. I was moved by the simple example which was outlined today of timescales. A lot of people think we have plenty of time to work out climate change by 2050 — but honestly, we really haven’t. We absolutely should not be creating any more emissions — and that means we shouldn’t be knocking down any more buildings.”