Michael Trousdell is the Head of Sustainability for Property and Buildings. With a diverse background in sustainable strategy, engineering design processes and building technology solutions, Michael is passionate about helping clients and colleagues leverage different solutions across projects to meet decarbonisation targets and drive regenerative project outcomes. His work involves balancing diverse objectives to ensure projects harness the best solutions and expertise for optimal sustainability outcomes.  

In this ‘In conversation with’ piece, Michael shares his views on the current state of the built environment, emerging trends and the crucial steps stakeholders must take to accelerate the industry's alignment with Net Zero standards.

There’s an increasing focus on retrofitting buildings and the benefit of reuse. This highlights how the built environment is embracing more of a circular approach, integrating this at not just a building level but also at a component level. This is currently driving a lot of policy discussions in the UK and many clients want to demonstrate leadership here. Clients are interested in delivering projects that have a high reuse component, pivoting to investing more in retrofits to align with the direction of the industry.

Alongside this, there has been a shift in the perception of sustainability and how this can broadly and positively impact building projects. In the 1990s, “sustainability” referred to the triple bottom line (TBL) or the three Ps: Planet, People and Profit. At this time, this was framed negatively as it was perceived that a trade-off needed to be made between one element and another, making it seem impossible to achieve benefits across all three Ps.   

However, this thinking has adapted following the UK’s commitment to the Paris Agreement. This has driven major industry reforms through the introduction of Net Zero standards and more sustainable design approaches like regenerative design, which is a holistic way of designing buildings that improves social outcomes, benefits natural systems while still minimising environmental impacts. The industry is changing its focus to being business positive, community positive and planet positive – breaking siloed thinking and making it achievable to have positive intersections between all of these things.

In fact, recent research shows that European office buildings with sustainability credentials can result in a 6% rental premium compared to non-certified buildings. This emphasises that a green building is more valuable in today’s market in comparison to the 90s, reflecting the impact of applying a coherent sustainability strategy.

An important thing to note about these systems is that they enable energy consumption to be optimised, while supporting the wellbeing of occupants. I presented at a conference in Copenhagen, which covered how building controls need to respond to the new European Energy Performance of Buildings Directive (EPBD). The legislation is making it mandatory for more EU buildings to report on energy performance, while also reporting on comfort metrics required to achieve a comfortable indoor environment for building occupants. Rather than turning heating off entirely, these smart systems can use CO₂ and temperature control data to adjust heating, cooling and ventilation dynamically to optimise both comfort and energy, saving costs without impacting occupant wellbeing.

How is material use in the built environment evolving in line with circular economy?

Circular economy manifests in practice in various ways, depending on the nuances of projects. For example, in terms of steel design, we have projects like Elephant and Castle, where software was used to compare structural sizes with available steel for reuse, leading to significant carbon savings. 

This principle also applies to floor tiles, where WSP has worked with demolition contractors to carefully remove and return tiles to manufacturers for reuse. In fact, some of our manufacturers now report that 70% of their market is reused floor tiles. For building services systems, recycling is quite common, especially for valuable materials like copper and steel. The recent refit of our Sydney office is a great example, where components like IT equipment and wall partitions were reused.

A key part of achieving this is by integrating circularity into design and construction processes. This involves writing circular economy clauses into construction and demolition contract documents, requiring items like floor tiles and ductwork to be sold or donated via online material bank platforms such as Material Index.  By correctly inserting these clauses into contract documents, this allows sustainability principles to not just be high-level ideas but to be implemented in practice.  

What practices can be implemented to improve sustainability for projects?  

There are various steps that built environment stakeholders can take for projects to limit carbon emissions and protect ecosystems. Below I’ve shared some key opportunities for clients to consider that I’ve noticed when working on projects.

Keeping on the topic of materials, another key consideration is the thermal performance of facades and how this impacts energy use. The industry has gone from using double to triple and now you can even buy quadruple glazed windows to create more energy efficient facades. However, this increased glazing performance comes at a cost, adding a lot more embodied carbon and other associated supply chain impacts   compared to simpler facade solutions. In this respect, it’s important for energy use and embodied carbon needs to be balanced. Given the UK’s relatively low carbon energy supply, double glazed windows typically deliver optimal outcomes for energy efficiency and sustainability, with triple glazing only required in certain cases. 

Beyond this, a key sustainability priority for construction is changing refrigerants used for heating and cooling systems, which includes heat pumps, chillers and refrigeration. Historically, refrigerants were bad for climate change as well as ozone depletion. However, this is no longer the case, with various natural refrigerant options, such as isobutane or propane-based solutions, available on the market but these must be correctly installed to mitigate risks such as pollution and flammability. Architects and clients need to work with engineers to find space outside for these heating and cooling systems. 

Another thing to consider is that many buildings in dense urban areas do not have the roof space to support this but district heating and cooling systems can be leveraged to support this at scale. Groups of three or four large heat pumps or chillers can supply hundreds of buildings from a single location. Achieving the best outcomes requires focus on inter-disciplinary design, where all parties carefully consider all facets of a project and collaborate with each other to determine the most appropriate solutions.

Embedding a circular economy approach at all levels is key to truly uncovering and leveraging benefits for businesses, communities and the planet.

We hope you enjoyed reading Michael’s perspective on the opportunities that exist for stakeholders in the built environment to accelerate towards a more sustainable future. Keep your eyes peeled for our next instalment over the coming months, where we’ll speak to another WSP expert and uncover their unique insights on the latest industry developments, among other things.