Circular construction methods

Circular construction… an important development in the Dutch construction sector. It also represents significant progress, as construction is the sector responsible for by far the largest amount of waste. Does circularity in this sector mean that new housing developments, both now and in the future, will mostly reuse existing materials from other buildings? Or will many new renewable products be used? And is circular construction much easier to apply in new housing than in renovation projects? This is what we asked Eva Starmans (advisor circular building & public procurement C2C ExpoLAB) and Yvette Govaart (urban producer COUP).

You are both working on the circular economy; how are you doing this?

According to Govaart, it starts with using what is already there, as much as possible. This is also reflected in the many repurposing projects in which COUP is involved. Govaart: ‘It makes us happy that we are able to provide a church with a new function, thus enabling sustainable conservation, or to take an ancient fortress and turn it into a publicly accessible building, allowing society to enjoy this heritage.’ BlueCity is another example. Govaart: ‘We are transforming the former Tropicana building in Rotterdam into a circular, model city. We do this not only from an ideological perspective, but also because we like the idea of exposing the various layers of a building and, thus, tell a certain story. This leads to richness and quality. That we do this as much as possible with reused material and products that can be used again is a matter of course for us.’
Starmans explains that C2C ExpoLAB primarily focuses on circular construction and procurement and tries to set the bar as high as possible within the established frameworks (i.e. budget, planning, quality). Starmans goes on to say: ‘In addition to advising clients with respect to the practical application of circularity in projects, we also address knowledge questions to accelerate the transition towards a circular economy. This concerns, for example, the financial residual value of materials and themes such as circular & healthy construction.’

What would be the definition of a circular building?

Govaart and Starmans agree that a circular building is primarily a valuable collection of materials, stored in such a way that they form a comfortable, high-quality building, which, in the long term, can easily be reused when the demand for space changes. Fit for future use. ‘And’, Starmans adds, ‘where attention is also paid to aspects of human health and collaboration, with new revenue models.’ According to Govaart, a circular building also has an optimal energy system, which ideally generates energy for its users and its environment.

What would be a good example of a building project with circularity as one of the starting points?

Starmans names Stadskantoor Venlo, the office building of the municipality of Venlo, which was an important catalyst for new circular developments at C2C ExpoLAB. Another great example is that of the municipality of Someren. Starmans: ‘The so-called Ecodepot scheme of the municipality of Someren encourages homeowners to use circular construction methods. This led not only to the first homes with circular applications, but also to the housing association having started its first project of 16 circular rental homes. The contractor they selected is, in turn, also using the knowledge gained in Someren in other projects. This ripple effect shows that starting something is more important than being perfect at it.’ Govaart agrees and indicates that there are many projects that capture the imagination. Such as not only the previously mentioned BlueCity but also includes the Green House in Utrecht. Govaart: ‘At Green House, use is designed mostly as a service; there is no waste and the kitchen uses as little electricity as possible.’

Focusing on the existing building stock would be the obvious approach to circular construction. Not only to prevent enormous amounts of waste, but also to avoid new natural resource extraction and its related environmental impact. However, a recent study by TNO shows that too few existing materials are becoming available to meet the demand for reusable material. How do we solve this shortage?

By also using new materials, as Govaart and Starmans conclude, but not without being very picky. Starmans: ‘New materials will need to be used, but it is important to choose those that can be reused again, in order to prevent future waste. These are materials of which the composition is known, which have been partly reused or can be reused after their current application comes to an end, and which do not contain any toxic substances.’ Govaart states that, when developing new materials, it is especially important to make the most optimal choices in design, development and construction processes. In addition, we also need to accept that our environment does not necessarily have to consist of brand-new materials. Govaart: ‘We have to realise that our world can also be very comfortable using well-designed reused materials. Changes are needed, not only on the supply side (the construction sector), but also with respect to demand, with clients and users having to think about what is actually expected and required, and what impact this will have on our physical environment.’

How is the insight gained into where reusable materials and products are located and/or when they will become available?

Govaart says that, at the moment, it is mainly a matter of calling everyone and everything, searching online platforms and establishing connections with demolition companies, in order to find enough suitable material in time for a construction project. In the future, Govaart sees a much larger, crucial role for Madaster and the use of material passports, provided the government also assumes its responsibility.

Govaart: ‘In Madaster, all building information and material properties can be coupled. This creates a gigantic material database that can be used by builders, contractors and architects in their designs, using the material that either is or is close to becoming available. The moment property owners are planning to dismantle or modify a building, this should become visible in the system. This also calls for a fixed method of valuing materials to counteract opportunism with respect to expectations of availability. The government should take a stronger role here, both facilitating and guiding.’

Will the many new renewable products in circular construction lead to the use of unwanted, environmentally damaging embodied energy (the energy associated with the production of all building materials in a building)?

According to Govaart, this largely depends on the materials as well as on the requirements that a building has to meet: ‘Sometimes you cannot avoid using high embodied energy materials, if that is what is required. The point is to have sufficient material knowledge to make informed decisions, in this regard.’

Are circular construction methods easier to apply in new buildings than in renovation projects?

According to Starmans, there is not much difference between both approaches; new construction and renovation both offer opportunities in this area. The construction of the Egerbos sports centre is a good example of this. Starmans explains: ‘One gymnasium was retained and circularly renovated, while another was demolished and circularly rebuilt. Certain materials from the old situation were partly reused. The bleachers, for example, were constructed from the old ceilings. And many circular materials were used in the newly constructed gymnasium — materials that can be reused at the end of use.’ Govaart adds that the application of circular construction methods in renovation often calls for more customisation. In addition, it is more difficult to predict what the performance will be of combining existing and newly added circular materials. Govaart: ‘This requires a certain amount of experimentation, for both users, clients and competent authorities.’

Which of the principles of circular construction are more difficult to apply to renovation projects?

According to Starmans, it is particularly the details that are a point of attention to ensure that future changes remain possible and materials can be reused, thus avoiding waste. Govaart adds, ‘When something new has to be connected to an existing building/construction system, often with different building code requirements, this almost always involves customised pieces and suboptimal dimensions. More customisation, which therefore also means more money.’

What would be needed to turn circular construction into the standard, in the Netherlands?

For starters, this would require a shift in taxation, according to Govaart. She argues: ‘This is really necessary. Lower labour tax and higher taxation of new materials (the so-called ‘ex-tax’ movement). In addition, the government needs to take on a much more active role in encouraging the construction sector and outlining where we stand with respect to the transition towards a circular Netherlands by 2050.’ She also emphasises that craftsmanship needs to be embraced far more than it is today: ‘Professionals need to be trained in aquiring far greater material knowledge. Creativity in seeing design opportunities using existing materials is key.’
Starmans and Govaart emphasise that, as a society, we need to become much more aware of the impact of our choices; this applies to the users of buildings, public spaces, products and services, as well as to professionals in the construction sector. Govaart: ‘How strange is it that we are used to ordering material from a catalogue, which is then shipped to us from the other side of the world, without us having any idea about the impact on our physical environment, and which is even cheaper and much easier and faster to use than material from the neighbourhood? Knowledge of the total Life Cycle Analysis of materials is indispensable.’ Including circularity in procurements or using it as a basic point of departure for new development projects also makes a difference, according to Starmans. Both agree that a can-do attitude is needed. Rather that applying project management that is based on minimising the risks (as is currently the way), we need to dare to let go and make an integral assessment that is based on time, money and quality as well as on sustainability — with all parties striving for and endorsing this ambition, on a daily basis. ‘Because,’ Starmans adds, ‘in order to build a circular future together, starting something is more important than being perfect at it.’