As world leaders prepare to gather for the 31st United Nations Climate Change Conference (COP31), the topic of resilient cities is high on the agenda. In the European Union, buildings are the single largest energy consumer, yet the renovation of Europe's building stock is progressing far more slowly than planned.

The world's biggest annual climate summit will take place from 9 to 20 November in Antalya, Turkey, and the Turkish COP31 Presidency has placed sustainable and people-centred cities at the heart of its agenda. They describe cities as the 'main arenas of climate action' because of their high energy consumption and greenhouse gas emissions – an issue caused, in a large part, by buildings themselves.

Resilient cities and the built environment are also a priority for the European Union. In July 2026, the European Commission opened infringement procedures against all 27 Member States for failing to fully transpose the Energy Performance of Buildings Directive (EPBD) into national law. The directive is the EU's main instrument for decarbonising its building stock and directly contributes to its energy and climate goals.

Europe's largest energy consumer

Eduardo Maldonado, Professor of Mechanical Engineering at the University of Porto: “If we want to fight climate change and energy dependence, we need to aim at reducing energy consumption from fossil fuels everywhere.”
Read the full interview with Eduardo Maldonado

Maldonado coordinated a task force supporting Member States in implementing the EPBD and defining national standards for nearly zero-energy buildings (NZEBs). “That being said, buildings account for 40% of energy consumption, and so we must make an effort to substantially reduce this impact.”

Buildings are indeed responsible for about 40% of energy consumption and 36% of energy-related greenhouse gas emissions in the EU. Much of Europe's building stock is old and inefficient: roughly 85% of EU buildings were built before 2000 and around three quarters are considered energy inefficient. At the same time, only about 1% of buildings undergo energy renovation each year.

Technical solutions for net-zero energy buildings already exist. What is missing, is a way to make them affordable. “The biggest challenge is affordability. Honestly, the majority of the European population cannot afford it,” says Maldonado. “It is technically possible to build net-zero buildings. We have the research and we have the technical solutions. Right now, it's a matter of costs.”  

Unmet targets

The EU has been working towards more energy-efficient buildings for more than two decades. Since 2020, all new buildings in the EU must be nearly zero-energy buildings. The recast EPBD, adopted in 2024, goes further: it replaces the NZEB requirement with a new 'zero-emission building' standard, which will apply to all new public buildings from 2028 and to all other new buildings from 2030. For existing homes, the directive requires Member States to cut the average primary energy use of residential buildings by 16% by 2030.

Member States had until May 2026 to transpose the directive, but none met the deadline. They now have until the end of the year to finalise their National Building Renovation Plans, which set out national roadmaps towards 2030 and 2050.

“None of the 27 Member States have met the intended targets, but the European Commission hasn't made the right conditions for them to reach those goals,” says Maldonado. “Member States were encouraged to help citizens, but the help is not significant enough. People are still expected to spend a lot of money on renovations, but the prices in construction have been increasing faster than in other sectors.” Not to mention that many citizens are affected by energy poverty, he adds. “Many people can't afford heating in the winter and air conditioning in the summer at today's prices. Prices of electricity keep going up as natural gas prices go up, independently of the increased share of “cheap renewable energy”, but at the same time people are expected to electrify their houses. We need to face the contradiction.”

Complex choices

Experts agree that costs are currently the main obstacle.

Inger Andresen, Professor in Integrated Energy Design at the Norwegian University of Science and Technology and coordinator of the EU-funded project 'Climate Positive Circular Communities': “Even if the solutions have positive lifecycle costs, the initial costs are too high for many people, and the financing options are still not great in many countries.” - Read the full interview with Inger Andresen

The biggest challenge concerns existing buildings, but even new constructions face a financial dilemma. Many countries urgently need thousands of new homes, and net-zero buildings cost more than traditional ones. “Where will this money come from? We need to consider this and balance the needs of the population,” warns Maldonado.

Turning an old building into a net-zero energy building is possible, but can be difficult – and in some cases, such as heritage buildings, it may not be viable at all. “In fact, this is why we started looking at the issue at a neighbourhood level rather than making changes building per building,” notes Andresen. Such approach might be much more effective and feasible, because “some buildings can compensate for others at a neighbourhood level”, she explains.

Moreover, renovation becomes more economical and efficient in neighbourhoods where buildings are similar, and the same solutions can be applied at once, Andresen explains. “It can be difficult for people to find the best solutions – because it differs from building to building.” To help homeowners navigate complex renovation choices, Andresen points to the development of “one-stop shops” that bring together different suppliers and services to offer residents a complete package. “We need to offer more of these services to make it easier for people.”

Are the targets within reach?

To achieve a higher rate of net-zero energy buildings, financing and regulations need to work together. “It is the carrot and whip principle. Regulations are the whip and the financing would be the carrot,” points out Andresen. At the same time, incentives don't always need to be purely financial. “We could offer faster approval of permits, for example.” And “soft” criteria, such as liveability and architectural preferences, must also be taken into account.

Importantly, the specific targets might need revisiting as well, suggests Maldonado. “It is now 25 years since we started this initiative, and the geopolitical circumstances have changed. We need to look at the global picture. What is the purpose of having a European green island that's net-zero if the rest of the world isn't doing the same? Europe is just a drop in the bucket of emissions. Reducing our emissions without others going along isn't going to make any difference. We need to think globally, not only locally.”

As such, Maldonado is sceptical and believes the 2030 targets can no longer be met, as the necessary regulations are not yet in place and would not deliver meaningful results in time, even if adopted now. “We should collectively, as Europeans, rethink our climate targets and the EPBD. Many things have changed and we need to come up with new realistic targets for net-zero energy buildings.”

Andresen is more hopeful. “I'm beginning to doubt that we will reach the 2030 targets, but there is still time – we just need to work hard. The goals of 2050 should definitely be possible,” she says. The next step, in her view, is for each country to follow up on its intentions and finalise its building renovation plans. “There are a lot of good intentions, but little is happening on the ground, also because there are many other things happening in the world that demand attention.”

Message for COP31

Ahead of COP31, both experts call on policymakers to connect climate ambition with the realities people face. “Be serious and promise only what you know you're really willing to do,” says Maldonado. “We should always aim at better energy efficiency, but let's do it in a realistic way, while taking economics into account. People need to think about their finances. Affordability is the key word here.”

The benefits of energy efficient buildings go beyond the reduction of emissions. Net-zero energy neighbourhoods, Andresen argues, improve not only the climate but the overall resilience of the EU and its citizens. “These solutions don't only provide environmental benefits, but also safety and security, because smart use of energy and producing energy locally makes Europe more robust.”

Related content:

• An expert’s opinion: Interview with Prof. Inger Andresen on the importance of developing net-zero energy neighbourhoods
• An expert’s opinion: Interview with Prof. Eduardo Maldonado on the main obstacles to more net-zero energy buildings