Efforts to halt catastrophic climate change are being held back by "inertia" in the built environment sector, according to Yamina Saheb, co-author of the latest report from the United Nations climate change panel.

"The sector hasn't modernised at all since the second world war," she told Dezeen. "And now, the data shows it's lagging behind all other sectors."

"Each gram of greenhouse gas emissions from buildings means a mistake in their design," added Saheb, a former policy analyst for the European Commission and the International Energy Agency.

"Architects and urban planners should really look at this report carefully and rethink the way they work."

Up to 61 per cent of building emissions could be cut by 2050 using technologies available today, the Mitigation of Climate Change report from the Intergovernmental Panel on Climate Change (IPCC) found.

But progress has so far been held back by widespread "inertia," as well as a lack of ambition and prioritising of short-term solutions and profits over long-term gains, Saheb said.

Architects are key to mitigating climate change

The report, which was written by Saheb alongside more than 270 scientists from 65 countries, is the final instalment in the IPCC's three-part review of the current state of climate science.

Following on from two earlier reports covering its causes and effects, the report sets out a plan for how global warming could be mitigated.

The decarbonisation pledges made by international governments in a bid to halve emissions by 2030 and reach net-zero by 2050 are simply not enough, the report found, falling short by as much as 23 billion tons of CO2e.

As a result, the world is on track to warm by more than double the 1.5-degree limit set out in the Paris Climate Agreement this century.

"Covering up for these shortfalls will require taking actions across all sectors that can substantially reduce greenhouse gas emissions," the report states.

The built environment is among the key sectors highlighted in the report that could help the world to cut emissions by 50 per cent this decade.

"Either get this right or it's wrong forever"

Urgent action is needed from the sector before 2030, the report says, as the long lifespan of buildings and infrastructure locks in emissions and polluting behaviours for decades to come.

"Residential buildings undergo major renovation once every 25 years," Saheb explained. "That means if you're not renovating a building to zero-emissions standards this decade, it will not be renovated to this level by 2050 either."

"For buildings, there is only one round left between now and 2050, so we either get this right or it's wrong forever."

Retrofitting is the single most effective strategy for developed countries to limit emissions from buildings, the report found. But so far, "low renovation rates and low ambition" have hindered large-scale emissions reductions.

This can be traced back to the construction industry's lack of digitisation, Saheb argues, and the fact that homeowners have to organise every element of a retrofit, from the heat pump to the insulation, by themselves.

"If you need to repair your car, you don't have to think about each piece separately," Saheb said. "You just take it to a garage, they fix it and you don't care about the details."

"But for a renovation, you as an individual are required to arrange all the details yourself, which is crazy and unrealistic," she added. "We should have IKEA kits for renovating our buildings."

"And in Europe, we need to make renovation mandatory to zero-carbon standards. If we don't have this required by law, it will never happen."

Sufficiency undervalued due to financial interests 

Crucially, the report also highlights that architects and urban planners have so far neglected to focus on designing for "sufficiency".

Unlike efficiency measures, which are marginal short-term technological improvements, this term is used to describe broader strategies such as passive cooling, bioclimatic design and prioritising the construction of denser multifamily homes.

These kinds of measures can drastically reduce a building's demand for energy, materials, land and water over its lifecycle, without relying on added technology and materials that will need to be produced, powered and maintained.

"If you design a new development with lots of single-family homes, you will need more land and more construction materials, as well as more energy and water in use than if you go for multifamily buildings," Saheb said.

"And then you lock the city where you're building into emissions and car-dependent mobility for generations. This shows how urban and land-use policies will play a major role in the decarbonisation of buildings, which was not considered before."

Part of the reason that this has so far been undervalued is the fact that architects and urban planners get paid based on a project's size, Saheb argues, so designing more compact structures runs against their financial interests.

"No one is questioning if the way they make money is aligned with their contribution to climate mitigation," she said.

Efficiency is not enough

The industry's failure to adapt sufficiency strategies so far has actually counteracted emissions reductions achieved by making buildings more energy efficient, the report found.

Adding insulation, switching to more modern appliances and other efficiency measures reduced building emissions by 49 per cent between 1990 and 2019. But the lack of sufficiency measures led to a simultaneous emissions increase of 52 per cent.

"The efficiency improvement was fully offset by the lack of sufficiency measures," Saheb said.

"Previously, climate mitigation policies for buildings included only energy efficiency and the supply with renewables. And we know today that without sufficiency, this is not enough."

The top image shows Maya Lin's Ghost Forest installation.