The UK is joining a global drive towards a ‘net zero carbon’ future, with its biggest cities setting ambitious decarbonisation targets in an effort to reduce their impact on the environment.
Manchester plans to be a carbon-neutral city by 2038, while Bristol aims for full decarbonisation by 2030. In London, all new buildings will be net zero carbon by 2030, as the UK strives to meet targets set by the Paris Climate Agreement.
“A transition to net zero carbon buildings is crucial if the UK is to deliver on national climate change targets to decrease carbon emissions by 2050 and keep global warming below 2 degrees celsius,” says Sonal Jain, Sustainability Director of JLL’s Building a Better Tomorrow team.
According to the World Green Building Council, a net zero carbon building is a highly energy efficient building which is fully powered by onsite or offsite renewable energy, in order for its operational carbon emissions to be zero.
Energy efficiency is a key aspect of net zero buildings, which might include passive design features that minimise energy use, such as natural ventilation or solar shading. The use of efficient technology and smart meters for lighting, heating and ventilation helps to monitor and optimise energy usage further, leaving only very little demand that can be powered by renewable energy.
Such features are relatively straightforward to incorporate in new builds but adapting older buildings to be net zero is more challenging – and new builds make up just 1-2 percent of the existing building stock, notes Jain. “Retrofitting existing buildings may involve updating a building’s energy source from, say, gas, to electricity, as well as integral layout and façade changes. These can be costly and difficult projects,” she says.
The impact of net zero
For many cities, a faster transition to a net zero built environment is a necessary investment.
Like Paris and Los Angeles, London’s building emissions make up some 70 percent of the city’s total emissions, compared to the UK average of 40 percent. “For these cities, a more ambitious net zero buildings transition is necessary to substantially reduce their overall emissions,” says Jain.
While the UK government has announced a £420 million construction sector deal to halve building energy use and emissions by 2030, London is one of 19 world cities that have signed the Net Zero Carbon Buildings pledge that all new buildings will be net zero by 2030, and all buildings net-zero by 2050.
In coastal cities such as Los Angeles that are at greater risk for climate change disasters such as flooding, ambitious carbon-reduction targets are a way to mitigate that risk.
“Some mayors also see an opportunity to boost the green economy,” says Jain. Research from cities network C40 has found that bolder green policy in building as well as transport would yield significant economic profit, while delivering benefits for another urgent concern of many world cities: air quality and its health impacts.
A global movement
For cities to meet their net zero targets, a rigorous standard on how to address the transformation of existing buildings will be crucial, says Jain.
“The current targets are progressive moves that bode well for meeting global climate targets,” Jain says. “What’s now required is a developmental framework for how to proceed.”
Regulations must set out how net zero buildings are to be assessed, including how often assessment takes place. “Many buildings that claim net-zero status today are based on simulated calculations rather than operational emissions,” notes Jain.
Policy must also define a clear structure for how responsibility over a building’s net zero credentials is shared between entities such as the landlord, developer and operator, to ensure no aspect of a building is unclaimed.
For businesses to take on the challenge and costs of retrofitting buildings, net zero programmes must create incentives for companies and stakeholders – and run these initiatives across entire cities.
“With climate change on the horizon, and the significant impact of building operations on overall carbon emissions, net zero buildings must become a defining feature of the built environment,” says Jain. “Construction is a global supply chain and a shift towards net zero building will require much collaboration. We are the very beginning of the net zero movement and delivery on these promising targets will take time – but there are strong signals we’ll get there.”