A circular building as a roadmap to Paris proof

How does circularity help reduce CO2?

In addition to day-to-day energy consumption, two key factors contribute to a building’s carbon footprint: the choice of materials and the choice of demolition or reuse.

To reduce the total carbon emissions during a building’s lifespan, it is important to start thinking carefully about this during the design process. Is a new building really necessary, or is it also possible to renovate existing real estate? Since fewer materials are needed for renovation, it is a better choice environmentally.

What materials do we need? Will you opt for rare primary raw materials or recycled or renewable (bio-based) materials? How do these differ in terms of the carbon emissions involved in sourcing or producing the materials?

There will also come a time when the building is no longer needed. Demolition is the least environmentally friendly option, so how do we ensure that everything can be dismantled and reused later on?

Materials transition an essential part of the energy transition

The energy transition and materials transition are inextricably linked when it comes to making buildings sustainable and future proof. If our aim is to reduce carbon emissions, we will also need to opt for sustainable materials that release less CO2 when sourced or produced.

This need is also reflected in laws and regulations. In Europe, a target has been set to reduce the carbon emissions of real estate by 55% by 2030 and 95% by 2050. When it comes to materials, the aim is to reduce primary raw materials by 50% by 2030. The target date for 100% circularity is 2050.

Legislation governing the use of materials has also been tightened. The environmental performance system for buildings (MilieuPrestatie Gebouwen, MPG) is a standard for the environmental impact of materials used in a building. The lower the MPG, the more sustainable the building is. For new buildings, it is mandatory to submit this MPG and the requirements are becoming increasingly strict. If you fail to comply with the MPG, you will not be given planning permission for your building.

Striking the right balance between choice of materials and energy performance

Although it may seem logical that sustainable materials contribute towards the energy transition, this can occasionally prove challenging in practice.

In addition to the requirements mentioned above, there are other guidelines relating to a building’s energy performance, such as the EPA label (Energy Performance Advice or Energieprestatieadvies in Dutch), the BENG calculation (BENG stands for ‘Nearly energy-neutral buildings’ or Bijna Energieneutrale Gebouwen) and the WEii protocol (WEii stands for Actual Energy intensity indicator or Werkelijke Energie intensiteit indicator). In order to improve energy performance, you might consider solar panels or insulation. However, these require materials that will negatively affect the MPG. Bio-based insulation could be an option. The production of a solar cell is sustainable (based on the raw materials used) and therefore positive in terms of the MPG but scores lower for energy performance.

This means that developing a circular building involves a constant effort to strike the right balance between the most sustainable materials and the optimum energy performance.

Reusing materials in a circular building

In the development of a circular building, the issue of how materials can be recycled or reused is considered right at the start of the design process.

If you plan to opt for reused materials, this may require changes to the design, which is not always possible. This is why it is important to start by considering how you can minimise the use of materials and only then consider how the essential materials might be reused at a later stage.

The circular demolition of a building enables you to keep carbon emissions as low as possible. Not everything is waste, and materials could be given a different use elsewhere.

If you opt for used materials for an existing building, you have to take account of the existing structure, which influences your choice of materials. The available materials previously used elsewhere for a different purpose need to match the existing design of the building.

On the other hand, in the case of a new-build, reused materials can be an excellent starting point for a new design. This also enables you to start thinking from the outset how the building can be made demountable, in order to enable the materials to be reused elsewhere later on.

Sustainable because it’s possible, not because it’s mandatory

At Royal HaskoningDHV, we are doing everything in our power to reduce the carbon emissions from our own buildings as rapidly as possible. With our mission ‘Enhancing Society Together’, we are not only helping our clients on their road towards the materials and energy transition but also applying our expertise to our own buildings. This includes making deliberate, sustainable choices in the use of materials for the renovation of our new office in Delft (opens in 2024). This former faculty building of Delft University of Technology (TU Delft) will soon be the Netherlands’ very first Paris-proof listed building!