It is crucial that we always ask if a new construction is needed. Preserving materials already invested in the built environment is paramount. Buildings are responsible for approximately 38% of global greenhouse gas emissions, with 28% stemming from operational energy use of existing building stock, and the remaining 10% coming from embodied carbon in materials for new construction and refurbishment. New annual construction only adds to a few percentage points of the existing building stock’s total area. However, their share (and that of building refurbishments) of the embodied impacts related to construction of building materials is significant.

Recent Danish studies show that emissions can be halved or even reduced by about 75% compared to current Danish legislation simply by following the best practice design strategies and materials available today. For new buildings, climate impact evaluation with LCA tools combined with ambitious commitments is of critical importance.

Creating global requirements for embodied carbon

Regulating carbon emissions through operational energy regulation alone is not sufficient to decarbonise the built environment. Evidence from whole life cycle carbon assessments of buildings reveals the increased importance of embodied carbon in building materials and components. To reduce it, new requirements need to be introduced with limit values. Those which have already been implemented or agreed in the Netherlands, France, Finland, Sweden, and Denmark for new construction should be encouraged worldwide.

Following design and materials best practices

Several studies on the carbon budgets of buildings in relation to planetary boundaries and Paris Agreement goalsshow that the carbon footprint of new construction far exceeds their limits. To meet our national and international commitments, much more ambitious commitments are needed, and architecture holds huge potential to make a difference. To translate the Paris Agreement and the Planetary Boundary for Climate Change into industry-specific reduction targets for new Danish housing projects, the “Reduction Roadmap” was developed by Danish consultants with research support from Danish Universities (see case in this chapter).

Furthermore, to enhance the development of low-carbon solutions for housing projects, philanthropic foundations have put focus on exploring and documenting 25 best practice cases with up to 75% lower climate impact than the current limit value in the new building regulation. These building projects have explored the use of different design strategies and new solutions, most often with increased use of biobased materials, but also with optimisation of the number of materials and careful choice of low carbon materials.

Optimising what already exists

Finally, focus should be on preventing demolition and prolonging the lifetime of existing buildings by renovation. This keeps valuable resources in the loop and provides substantial environmental benefits. When done cleverly, renovation can also contribute to important reductions of the operational climate impact of existing building stock. Recent Danish analysis shows a large variation in the environmental benefits of renovation and points out that solutions and materials must be chosen carefully.