Mr Rees told the UKREiiF conference in Leeds that sustainability shouldn't just be a matter for individuals making lifestyle choices, but was instead about those with power changing the infrastructure and systems that would deliver - or fail to deliver - sustainability.

Bristol mayor Marvin Rees said; ”If we sort cities out that will go a long way to sorting out our global problems.  But if we get urbanisation wrong, it will be a disaster.”

He warned that climate change was sometimes seen as a "middle-class pastime" rather a pressing concern for some of the most vulnerable people in society. And he warned changes aimed at bring about sustainable solutions had to be cost-effective for people who had suffered a cost of living crisis not just in recent weeks, but "for a very long time".

Mr Rees - whose role is being scrapped after a referendum in Bristol - said his proudest moment had been delivering 9,000 new homes in Bristol. And he said achieving a truly sustainable future would take more than political will, saying it had to be properly funded by a government that allowed long-term planning rather than repeatedly asking local authorities to compete for small pots of money.

He was speaking in conversation with our Chair Jason Longhurst who is also Strategic Director of Place at Bradford Council, at the Beyond Net Zero pavilion at UKREiiF in Leeds.

The first day's sessions in the pavilion had a number of key themes, including the importance of delivery - rather than promises -  and the importance of innovation in achieving measurable change.

In a session on sustainable development and place, sponsored by Keyland, titled "Will the next generation thank us for what we leave behind?", Claudine Blamey - head of sustainability and digital strategy at Argent - explained how technology had a key role to play in the buildings of both the future and present.

She said proptech was a "massive" area for Argent, who used it to measure things like usage and efficiency for maximum gains.

"We are going whole-heartedly after proptech," she said. "Without the technology in buildings we are not going to get to zero carbon."

Ms Blamey said money was available to finance developments providing property firms could make good on environmental promises.

"We have got green financing. If you are building the right buildings and infrastructure there is money out there but you have to deliver [zero-carbon]," she said. "Customers are asking for it. Their employees want to be working in a sustainable way.

"Developers have no excuses any more. There are no vicious circles. They have all closed up."

The session also heard from Jerry Tate, founder of Tate and Co Architects, and Euan Hall, chief executive of the Land Trust.

The Beyond Net Zero pavilion is sponsored by UKBCSD in partnership with City of Bradford Metropolitan District Council, with UKBCSD members Sir Robert McAlpine and Keyland Developments as key sponsors.

Tracy Brabin, Mayor of West Yorkshire, opened the pavilion with a keynote address.

She reflected on families being pushed into poverty and struggling with the cost of living, and spoke of households being affected by flooding on an increasingly frequent basis. She revealed that air pollution was now responsible for one in 20 deaths in West Yorkshire.

The Mayor said that there was an opportunity to tackle climate change by levelling up the UK if resources were concentrated on clean growth.

In response Mr Longhurst highlighted how Bradford was looking beyond net zero and aiming to become the UK’s leading clean growth city district through development’s like Esholt, the UK’s largest clean growth test bed, with one million square feet of sustainable commercial property space for biotech, agritech and cleantech firms.

He told a packed-out pavilion that UKBCSD members were focussed on delivering clean growth testbeds which the public and private sector could learn from rather than making undeliverable promises and pledges.

In a session entitled Creating a Clean Economy through Digital Transformation, Founder and chair of DiverseCity Surveyors, Bola Abisogun, Joseph Daniels, Board member of UKBCSD and founder of Etopia, Matthew Kirkman, Director of Infrastructure Solutions at Openreach and Savannah de Savary, founder and CEO of Built-ID, highlighted how high-quality, smart homes and buildings, powered by fibre broadband, enabled people to live and work more sustainably at a time when millions of people had adopted a hybrid working model.