BR18's climate requirements: CO2 limits for new construction

Construction accounts for a large part of Denmark's total carbon footprint — both from the materials used and from the construction process itself. The Building Regulations (BR18) for the first time in 2023 set a specific figure for how much CO2 a newly built house may emit over its lifetime and the requirements have since been tightened.

§2023: the first limit values

From 1 January 2023 it became a requirement that builders develop a life cycle assessment (LCA) for all new construction. Since then new buildings over 1,000 m² have had to meet an upper limit of 12 kg CO2 equivalents per m² per year for total climate impact calculated over a 50-year period.

§Summer 2025: requirements tighten significantly

From 1 July 2025 climate requirements apply to all new construction regardless of size — not just buildings over 1,000 m² as before. At the same time the average limit is significantly lowered from the previous 12 kg to about 7.1 kg CO2 equivalents per m² per year and is planned to be lowered further in coming years.

§The limits are differentiated by building type

For the first time BR18 operates with different CO2 limits depending on the type of building being constructed. A single-family house or row house has a different slightly lower limit value than an apartment building or a commercial building because the building types have different typical material quantities and operating patterns. The differentiation is meant to make the requirements more fair across the building industry's very different project types.

§A new boundary for the building process itself

Beyond the building's overall lifetime carbon footprint, an independent threshold is introduced for climate impact from the construction process itself — that is, transport of materials and equipment to the site, energy consumption on the building site and waste management along the way. This part of the footprint must be kept below 1.5 kg CO2 equivalents per m² per year and is included as a separate part of the overall life cycle assessment.

• 01Transport of materials and machines to and from site counts
• 02Energy consumption for machines heat and lighting on site counts
• 03Handling and disposal of construction waste counts
• 04The requirement should push construction sites towards less waste and greener operation, not just greener materials

§Responsibility lies with the client, but decisions start early

It is the project owner who is formally responsible for ensuring that a project meets climate requirements, but the crucial decisions are often made already in the design phase — in the choice of construction principle, materials, and building size. The earlier in a project the carbon footprint is considered, the cheaper and easier it is typically to comply with the limit, because you can choose other solutions from the start instead of having to correct them later.

§What does it mean for construction workers?

For craftspeople and contractors the requirements mean the climate account is no longer something architects and engineers calculate at the desk — it is something that must be documentable for the specific construction site. Material choice waste transport and energy consumption on site become all figures that count towards the overall calculation and which each individual employee's working methods help influence.

It places new demands on documentation out on site: quantities of material must be accounted for waste must be recorded and transport of materials must be documented. The craftspeople and foremen used to keeping track of these figures will experience that their daily record keeping gets a clear place in a larger statutory account.

• 01Climate requirements apply to all new construction from summer 2025 — regardless of size
• 02The limit value is differentiated by building type
• 03The building process has its own independent limit value of 1.5 kg CO2e per m² per year
• 04Early choices in design have a significant impact on whether requirements can be met