Our Sustainability Plan

With the global population expected to grow by 1.5 billion people by 2050, the construction industry will face an increasing demand for space while needing to drastically reduce its environmental impact. There is an urgent need to find a balance between meeting this growing demand while minimizing the environmental impact of our industry. Climate change, biodiversity loss, and resource depletion must be mitigated by shifting to sustainable practices in all sectors, particularly construction.

Every half-degree increase in global temperature will multiply the consequences, especially for vulnerable populations. Change must happen now, as we are already required to reduce emissions by 43% by 2030 and 60% by 2035 in order to reach net zero by 2050.

As architects and engineers, the choices we make have significant weight. The building sector accounts for nearly 37% of global carbon emissions, with structural materials being a major contributor. By optimizing material usage and focusing on embodied carbon, we can make a substantial difference. For example, reducing structural material use by just 20% for one engineer could save up to 200 tons of CO2 per year which is 33 times more impactful than not flying, adopting a vegan diet, and not driving for an entire year.

Minimizing Material Use, hence Quantity. We prioritize reducing material usage through design by focusing on reuse, refurbishment, renovation, optimizing designs through integrated and early involvement, and ensuring streamlined construction processes.

Maximizing the Life Cycle of Structures, hence Quality. We focus on creating adaptable, resilient, and long-lasting structures that evolve with time, minimizing the need for demolition or extensive reconstruction.

We are constantly evaluating the carbon footprint of all ongoing projects and have also analysed our past projects to gather insights. This allows us to adapt our designs to new benchmarks and learn what works and what needs to be worked on.

Observations for buildings

We have reviewed the GWP/m² of approximately 75 projects, classified by year, with the classification ending in 2023, as projects started from 2024 onward lack sufficient detail for direct comparison. The key lessons learned from this analysis are as follows:

• Renovation consistently outperforms new construction.
• Our recent projects show better results due to a stronger focus on renovation.
• Higher loads and larger spans have a significant impact on the GWP/m².
• Timber and hybrid structures (steel-timber and concrete-timber) tend to perform well when the design is carefully adapted.

Observations for bridges

The same principle has been applied to our infrastructure projects. To date, we have reviewed approximately 60 projects. In this case, the graph was adjusted to account for spans, as they significantly impact material usage and environmental impact. The lessons learned from these comparisons are as follows:

• Larger spans result in a higher GWP per square meter, exhibiting a linear relationship between the two variables. However, a noticeable inflection point occurs at approximately 40 meters, beyond which the additional GWP per meter of span decreases.
• Railways bridges have the highest GWP driven by heavy load demands. Footbridges and road bridges have similar GWP values influenced by the larger spans and the inclusion of service vehicles in footbridges.
• No notable GWP differences is seen between steel, concrete or hybrid bridges. Timber bridges however show notably lower GWP values.

  

We use the SCORS rating system developed by the Institution of Structural Engineers for benchmarking, it ranges from A++ to G, based on data from hundreds of projects across the UK. This system provides a clear benchmark for the expected GWP per square meter.

Using the SCORS system and the 2017 Global Status Report, which allocates a global carbon budget of 21 GtCO2e for construction until 2050 and estimates 5.3 billion m² of new construction annually, we have set long-term targets for our projects. Our ambitious goal starts with an E rating and aims to reduce emissions by about 10% per year, ultimately reaching zero emissions by 2050. The values below are given in kgCO₂eq/m².

We find the SCORBS rating system limited for bridges, as it does not account for span. Therefore, we have developed our own rating system, which is based on SCORS averages and insights from our own projects. The SCORBS values are used as a reference point at our inflection point of 40m, with the shape of the linear relationship applied to define the limits of our benchmarks.

As for our targets, we aim to reduce our average GWP per square meter per span by 10% annually, similar to our approach for buildings, with the goal of reaching net zero emissions by 2050. The values below are given in kgCO₂eq/m².

In our view, the quality of a structure can be measured by its potential lifespan. Low GWP structures with a short lifespan are counterproductive; we need to adapt our design to aim for adaptable, resilient and timeless designs that encourage repurposing rather than demolition.

The design considerations for infrastructure and buildings differ due to the distinct challenges each type of structure presents:

• For infrastructure, we notice that lifespan can be heavily influenced by factors such as detailing, maintenance needs, climate durability and the ability to adapt to changing user needs.
• For buildings, studies show that only 14% of buildings are demolished due to structural issues; the majority are demolished due to a lack of adaptability.

The experience we have gained over the past 30 years has led to a set of internal design guidelines, which are evaluated for each project considering its specific context and constraints.

Our studies are providing valuable insights into the impact of our work and how we can control it to reach our goal of achieving net zero by 2050 while meeting the increasing demand for construction. We are aiming for a 10% annual reduction in the carbon emissions of our infrastructure and building projects.

Reaching this target requires a collective effort—from design teams and contractors to lawmakers and material producers. However, we are committed to minimizing our environmental footprint through design alone, without waiting for external changes.

To accomplish this, we must go beyond conventional approaches, critically challenge every brief, and balance carbon investments with client goals. Our focus is now on renovation, reuse, and circularity, while adopting a two-pronged approach in our design: minimizing material quantity and maximizing lifespan through adaptable time-less design.

Moving forward, we will focus on a new challenge: shifting from simply minimizing our impact to actively improving environmental conditions through resilient design.

Our vision, insights, and results from our project evaluations, training sessions, literature, and discussions are compiled in our Sustainability Plan, authored by Corentin Leterme, with contributions from Toon Maas, Raphaël Cornelis, Jeroen Vander Beken and Pierre-Yves Adant. A general overview is provided here, and we encourage those interested in the full document to contact us.