Denmark has the reputation of taking on a pioneering role in sustainable construction. In 2023, Denmark integrated climate impact requirements of new buildings into its building regulations.
With this initiative, the country became the first in the world to introduce mandatory CO2e emission limits for new buildings over 1,000m2 – setting the precedent for sustainable construction. As of 2025, Denmark has strengthened the framework and further lowered the regulatory limits on carbon emissions throughout a building’s lifecycle.
Peter Konnerup, Associate Director in our Copenhagen office and Gry Lodahl Haxholm, Structural Engineer, discuss the implications of the updated building regulations (BR18) for the Danish construction industry, what they could potentially mean for other countries, and how Buro Happold is preparing to meet the new, lower thresholds.
Key updates to Denmark’s building regulations (BR18)
In 2023, the first phase of new requirements was introduced into the Danish building regulations which defined a threshold limit value of 12kg CO2e/m2/year for new buildings larger than 1,000m2. This threshold value comprised building related greenhouse gas emissions from life cycle phases A1-A3, B4, B6, C3, and C4. Phase two, which came into force in 2025, updated the framework and lowered the limits, with two more phases coming in 2027 and 2029.
Lowered CO2e thresholds: One of the most significant changes is the reduction of the average CO₂e limit from 12 kg/m²/year to an average of 7.1 kg/m²/year.
Expanded scope of applicability: The requirements apply to almost all new constructions, including those over 150m2. Some buildings such as hospitals, prisons, buildings for water- and energy supply and similar, are exempted.
Typology-based limits: Unlike the previous one-size-fits-all approach, the updated regulations introduce specific CO₂e limits for different building typologies, such as offices, residential buildings and schools.
Life cycle stage requirement: The required climate impact reporting will now be based on the following life cycle phases: A1-A5, B4, B6, C3, C4, and D. However, the requirements must be met without including the possible gains from stage D (reuse, recovery and recycling potential). Furthermore, the construction phase emissions from A4 and A5 must be calculated and reported separately and have its own limit value of 1.5 kgCO2e/m2/year.
The chart below illustrates the current updated CO₂e limit values for new buildings in 2025, along with the expected reductions in 2027 and 2029. It also compares these updated targets with the original forecasted limits, highlighting how the new regulations are now more stringent than initially anticipated.
What the new rules mean for the industry
For Buro Happold’s Gry Lodahl Haxholm and Peter Konnerup the updated building regulations reflect a clear ambition of the Danish government to remain at the forefront of embodied carbon legislation, which are essential to level the playing field and ensure consistent progress. Authorities must now continue to refine the framework to support this momentum in the industry.
They see the most impactful changes in the differentiation of requirements based on building typology and the introduction of a specific emissions limit for the construction phase. These updates provide practical tools to direct efforts where they can make the biggest difference – toward building typologies with the greatest potential for CO₂ reduction, such as family housing and residential buildings, which account for most new construction in Denmark.
The construction phase requirement is especially significant. It helps elevate life cycle assessments from being a design exercise to something that has real-world impact on a construction site. Everyday decisions – like leaving heating and lights on overnight at the construction site or operating diesel machinery – will now be reflected in the carbon accounting.
A step forward but falling short of Paris Agreement
The 2025 CO₂e limits send out a strong signal, but are they Paris proof? The answer is no because the new thresholds fall short of the ambitions set by the industry itself. Since the first requirements were introduced, many stakeholders in the Danish building industry have been calling for even stricter requirements. More than 600 companies – Buro Happold included – joined the “Reduction Roadmap” initiative, asking to base the limit values on the Paris Agreement and advocating for a maximum of 5.8kg CO2e/m2/year. However, the hope is this update will be a positive momentum and inspire the industry to continue to work toward a built environment that operates within planetary boundaries.
Focusing on reducing carbon emissions from new buildings is good but it is not good enough. We need to look at sustainability in the construction sector in a more holistic way. I hope the Danish government will implement additional environmental impact categories in the limit values to avoid the burden shifting between different ecosystems. We need to base the regulations on absolute sustainability and the science of planetary boundaries to truly understand and reduce the harmful impacts related to the building industry.
– Gry Lodahl Haxholm
Global perspectives: How other countries are approaching CO2 limits
The updated Danish BR18 requirements have sparked valuable discussions across Buro Happold’s global sustainability network. A key topic is the challenge of aligning climate targets and benchmarks internationally. Each country approaches carbon limits differently, shaped by local climate conditions, material availability and construction practices, making harmonisation complex but essential.
Knowledge sharing plays a central role in overcoming these challenges. Buro Happold’s sustainability ambitions are shared globally across all offices, with the understanding that meaningful change in the built environment can only be achieved through collective effort. Best-practice examples are frequently exchanged, allowing innovative solutions to be implemented more widely. While Denmark leads with legislation enforcing CO₂ limits, other countries excel in areas such as low-carbon materials, reuse of structural elements and regenerative design frameworks. This cross-border collaboration strengthens our ability to push boundaries and deliver sustainable outcomes in all regions.
Evolving CO₂ regulations across Europe are closely monitored. For instance, the Netherlands is tightening its MPG score limits, Poland is developing a national whole-life carbon assessment method and Germany is shaping its market through benchmarks from funding programmes and certification schemes like QNG and DGNB. These differences highlight the importance of international dialogue and shared learning.
How computational design tools facilitate sustainable design
To support compliance with Denmark’s updated building regulations, Buro Happold has developed tools to guide sustainable design from early concept to final decision-making.
Floor configurator: Empowering early-stage decision or real-time carbon insights
The Floor Configurator is an interactive tool designed to quickly assess the environmental impact of various framing systems, such as timber, hybrids, steel and concrete. Used in live sessions with clients and collaborators, it enables rapid comparison of structural options and fosters active participation in selecting the most sustainable solution. It is particularly effective during early-stage design and competitions, helping teams align with carbon targets from the outset.
Rapid prototyping: Framework for holistic design optimisation
Our rapid prototyping framework supports complex transformation projects by testing design variations as they evolve. This multidisciplinary, data-driven process evaluates a building’s performance across key parameters including spatial efficiency, indoor climate, LCA, cost, energy use and buildability. Presented in an interactive format, it enables transparent decision-making and helps identify optimal strategies for both new builds and complex transformation projects.
The most sustainable building is often considered one that is never constructed. Nonetheless, the updated building regulation requirements in Denmark represent a significant step toward a more sustainable construction sector. Achieving true sustainability, however, involves more than meeting carbon targets or selecting low-carbon materials. It requires a holistic approach that integrates climate, biodiversity, and social considerations across the entire lifecycle of a project.