Alongside the hum of traffic, the soundtrack of most cities includes the noise of construction workers drilling, hammering and digging as they furiously erect new buildings.
In fact, every five days the world adds structures equivalent to the size of Paris. Yet the way humanity constructs and operates buildings is unsustainable, say experts.
In 2022, energy-related carbon dioxide emissions from building operations and construction hit a new high, rising to 10 gigatonnes, according to a recent report from the United Nations Environment Programme (UNEP). That is 37 per cent of global carbon dioxide emissions.
“Reducing the carbon footprint of our homes, offices and other buildings will be essential to meet the targets of the Paris Agreement and averting a climate catastrophe,” said Ruth Coutto, Acting Chief of Climate Mitigation at UNEP. She added that reducing building emissions must be part of a larger, more ambitious global effort to counter climate change.
Here is a closer look at how buildings are feeding the climate crisis and how to make them greener.
What is the link between buildings and climate change?
The built environment – the place where people live, sleep, work, and play – is a major source of carbon dioxide. This greenhouse gas traps heat near the Earth’s surface, warming the planet and driving climate change.
Why are buildings such a major source of carbon dioxide emissions?
There are two reasons. Firstly, buildings use vast amounts of energy for heating, cooling and lighting. In 2022, the buildings sector accounted for 34 per cent of the world’s power consumption, found UNEP’s Global Status Report for Buildings and Construction. In many countries, energy is generated mostly from fossil fuels – like coal and oil – which release carbon dioxide when burned. This is what is known as operational carbon.
Secondly, buildings are full of steel, cement, aluminium and glass, which require a lot of energy to make, transport and install, again generating carbon dioxide emissions. This is what is known as embodied carbon.
Are we on track to decarbonize the buildings sector?
No. Global building sector emissions are still rising, jumping one per cent between 2021 and 2022, found the Global Status Report for Buildings and Construction. While that might not seem like much, it is equivalent to adding 10 million cars to the world’s roads. The report finds the sector remains off track to achieve decarbonization by 2050. In 2022, just six per cent of the energy used in buildings came from renewable sources. That is a long way off from a target of 18 percent by 2030 envisioned by the International Energy Agency.
How urgent is the need to make buildings greener?
Very. Half of the buildings that will exist by 2050 have not yet been built.
Unless the world changes how buildings are built and used, there will be little chance of meaningfully addressing climate change, which will lead to, among other things, more extreme weather. That is not something the planet can afford. This is why near-zero-emission buildings need to be the new normal by 2030. That is one of the key aims of the Buildings Breakthrough, an international effort led by UNEP to rein emissions in the sector.
What can be done to reduce building-sector emissions?
Humanity must reduce both operational and embodied emissions from its buildings. To reduce operational carbon emissions, buildings must become more efficient, cutting the amount of energy they use for things like heating and cooling. This can be done through the adoption of higher energy performance standards for new buildings, the retrofitting of existing buildings, the use of more efficient appliances, better energy planning and system integration. The use of renewable energy to power buildings must also be increased.
Will that require more investment?
Yes. Humanity will need to increase how much it spends on making its buildings climate friendly. Investments in decarbonizing structures reached US$285 billion according to the Global Status Report for Buildings and Construction. But that number fell short of targets for 2030 and 2050. To make matters worse, investments were forecast to have fallen slightly in 2023.
How can the world reduce embodied emissions?
A UNEP-backed report, Building Materials and the Climate, outlines a three-pronged solution: avoid, shift and improve. First, embodied carbon emissions can be avoided by building with fewer materials reusing building components, and repurposing existing buildings as part of a more circular approach to construction. Second, it is important to shift to more renewable, sustainably sourced bio-based building materials, such as timber and bamboo. Third, humanity must improve and lower the carbon footprint of conventional materials, including concrete, steel and aluminium. This can be done, for example, by using renewable energy in the manufacturing process.
All these measures combined can help put the world on the path to net-zero carbon emissions in the buildings and construction sector by 2050.
What can governments do right now to lower the carbon footprint of buildings?
Several things. First and foremost, governments can develop and enforce climate action roadmaps for buildings and construction. Some 161 nations have yet to do this. Governments can ensure building energy codes are aligned with zero-emissions building principles. They can incentivize investments in building decarbonization and develop policies to reduce embodied carbon through sustainable practices and materials. They can also promote the retrofitting of older buildings to slash energy consumption.
Countries could also join the Buildings Breakthrough, launched last year at the UN Climate Change Conference, and endorse the Declaration de Chaillot, unveiled at the Buildings and Climate Global Forum, to boost international cooperation. Implementing the commitments laid out in these frameworks can help countries to achieve the sustainable transition of the buildings sector and more widely, the goals of the Paris Agreement on climate change.
The next round of country-level climate commitments, known as Nationally Determined Contributions, also offers leaders the opportunity to develop clear targets for the buildings sector.
The Sectoral Solution to the climate crisis
UNEP is at the forefront of supporting the Paris Agreement goal of keeping global temperature rise well below 2°C, and aiming for 1.5°C, compared to pre-industrial levels. To do this, UNEP has developed the Sectoral Solution, a roadmap to reducing emissions across sectors in line with the Paris Agreement commitments and in pursuit of climate stability. The six sectors identified are: energy; industry; agriculture and food; forests and land use; transport; and buildings and cities.
