Circular construction and CO₂ impact
In 2023, we made solid progress in the development of our refined 2030 strategy, in which sustainability plays an essential role. On the sustainability front, our primary focus for 2030 is on climate (CO₂), biodiversity and water. In terms of the sustainable use of materials, this refined strategy means that not only does circular construction aim for the endless circulation of raw materials in functional cycles, but also for an increasing focus on their environmental impact and CO₂ emissions. A significant portion of Heijmans’ CO₂ emissions (scope 3) is related to the use of materials in our projects. Heijmans will continue to play its role as Master of Material Streams and we will continue to take responsibility for organising this in the chain and bringing organisations together. To this end, we have applied material flow analysis as a first step in several projects. We list a number of examples below per business unit.
Property Development and Residential building
At Property Development and Residential building, we identified material flows for all residential concepts in 2023. For both the concrete and timber-frame houses and the stacked (apartment) concepts. This gives us a total overview of material use, which means we can now focus directly on the most damaging materials. To clearly communicate the need to reduce the CO₂ emissions of materials internally and externally, we have embraced the Paris Proof method (striving to make the built environment completely climate-neutral by 2050). This involves determining the permissible CO₂ emissions of materials per home based on the available CO₂ budget in line with the Paris Climate Agreement.
We took a major step forwards on the sustainability front with our timber-frame house production plant in Heerenveen, where we produce our timber-frame houses on an industrial scale. At the end of 2023, we completed the first homes for a project in Eindhoven. These timber-frame houses score better on raw material use and environmental impact/CO₂ emissions than the current concrete variant. We have started the first studies on this topic. We also took our first step towards a timber alternative for stacked houses in 2023.
The Dutch national forestry commission (Staatsbosbeheer) and Heijmans have joined forces to incorporate OSB board material made from timber from Dutch forests in timber-frame houses produced according to the Horizon concept. Each year, Staatsbosbeheer supplies logs to West Fraser’s plant in Genk, Belgium, which West Fraser then processes to produce 40,000 m3 of OSB board material under the Hollands Hout label. The raw material comes from Staatsbosbeheer’s forests and is FSC certified.
Why Heijmans chooses to use FSC timber
FSC forest certification ensures not only that the forest area is preserved, but also that the forest is managed in a way that preserves its biodiversity. The earth desperately needs biodiversity to cope with climate change. For instance, grasslands with a higher diversity of grasses and herbs are more stable in providing ecosystem benefits under highly variable weather conditions. This is why Heijmans uses FSC-certified wood in our Horizon housing concept and others.
We teamed up with Europrovyl to make window frames more sustainable. We conducted a pilot project with sustainable plastic window frames in Pijnacker, installing completely fossil-free window frames without polluting PVC.
In addition, we started a collaboration with Heembeton and SQAPE for the production of cement-free concrete shells. This uses geopolymer as an alternative binding agent to cement, which can lead to significant environmental gains. The validation certificate for this was issued in December 2023 and we are working towards the realisation of the concrete shells in early 2024.
Non-residential
Non-residential completed most of the circular renovation of the Rabobank headquarters in Utrecht in 2023. In this project, we realised several circular interventions based on material flow analysis, including the use of circular concrete, cellulose insulation material, demountable internal walls and reused plasterboard. This led to a 23% reduction in the share of primary raw materials, which in turn led to a 55% reduction in material-related CO₂ emissions. Completion is scheduled for early 2024.
Another project is De Nieuwe Post: the renovation of the government offices at Stationsplein West in Arnhem. Together with the Central Government Real Estate Agency, we have set the bar high in terms of circular construction and this theme is central to the design process, which started in 2023. We have set clear targets for this project with regard to incoming and outgoing material flows, with the aim of closing the related cycles as much as possible. The New Normal, a market-wide framework that Heijmans also signed in December 2023, forms the basis for ambitions set. For example, one ambition is that 70% of the materials used in the building should have a secondary or renewable origin. In addition, 90% of the materials used must be able to be reused or recycled to a high degree in the future. We are already making great strides by constructing the top of the building entirely in timber, using a significant proportion of renewable materials. We also involved the supply chain early on in this project, so everyone can contribute to the reuse of materials. For instance, we have teamed up with a demolition company to make an early inventory of the materials that are released and record them digitally. We also looked at the opportunities for reuse with various suppliers. Furthermore, we have identified risks related to quality, transport and storage. By setting these concrete, circular ambitions, together we are gradually creating a chain-wide ecosystem in which Heijmans takes the helm as a sustainable leader.
In the field of circular management and maintenance, Heijmans has taken new steps in various maintenance contracts to make the required materials circular. Among other things, this means even more circular alternatives for common maintenance activities, such as the maintenance of pumps, filters and air treatment units. We also make Building Circularity Index (BCI) calculations for buildings. We use this methodology to measure the sustainability, reusability and detachability of any materials used. We can then use this data to provide our clients with insights into the (potential) sustainable results of circular management and maintenance.
Infra
Heijmans Infra Schiphol has applied several measures to realise the joint sustainability ambitions of Heijmans and Schiphol Airport in the MC2019 Lot 1 contract. Due to the huge numbers of materials and products that Heijmans processes at Schiphol, saving or reusing material yields enormous sustainability gains. Based on an impact analysis of circularity, Heijmans defined the prioritisation of product groups at Schiphol. On this basis, Schiphol and Heijmans employees have formed working groups for ongoing cooperation. This includes the product groups asphalt, concrete, markings, lighting fixtures and bases. In the case of asphalt, for example, we realise high-quality recycling of the asphalt that is released. Together with Schiphol Airport and Volker Wessels, in 2023 we opened a circular materials hub aimed at a high-quality closing of the concrete circle. Together with the supplier of the lighting fixtures, we have realised an initial return pilot in which we are having 1,400 runway lights reconditioned for reuse. These initiatives contribute both to reducing the CO₂ footprint and to less depletion of raw materials.
Heijmans Infra went through various processes in the field of circularity in 2023. Some of these developments have led to concrete sustainable products and reductions in waste flows, but also to pilots that have already resulted in concrete successes in a number of cases. Via regional hubs, for instance, we are gaining experience in realising local storage of reusable raw materials, helping us to minimise transport movements.
We have launched innovations in the field of recycling fine granulate as secondary raw material, applying sustainable wear layers (secondary crushed stone) and a self-cleaning gutter for microplastics. In practice, we apply self-healing concrete with less reinforcement. On the A1 Apeldoorn-Azelo project, a pilot is in progress for the use of alternative binding agents in concrete, aimed at reducing CO₂ emissions by about 75%. We are doing this partly with our cooperation partners.
For example, in the project to widen the N59 link road, we installed our circular guide rail with electric equipment. We dismantle steel that is good enough for reuse, measure it and check its quality. We de-galvanise the steel and then
re-galvanise to the original quality of new guide rails. Combined with the installation of a charging square in collaboration with Greenchoice and Green Energy Storage, the use of HVO100 biodiesel and sustainable asphalt mixtures, we saved 4,467 tonnes of CO₂ on that project.
In the project to widen the A1 motorway between Apeldoorn and Twello, our ambition is to work 100% emission-free. We have gained a lot of experience on this project in areas such as electrification, working safely and working with charging facilities. We embed the acquired knowledge in processes and use as much of it as we can in other projects. We also share our knowledge with cooperation partners, clients and knowledge networks. In addition, we applied the environmental cost indicator (ECI). To lower the ECI, we conducted a trial using circular concrete together with the Rutte Group. This circular concrete is sustainable quality concrete and made from demolished concrete rubble.
At the Attero production site in Wilp, we produced 32 massive girders. These girders will be used to widen five existing structures: Zuster Meyboomlaan, Oude Apeldoornseweg, Kayersdijk and the Bridge over the Apeldoorn Canal and H.W. Lordensweg. Allowing the girders to cure for 28 days before demoulding (instead of one day) eliminates the need to add additives that shorten the curing time. Also, less cement is needed to achieve the required demoulding strength. In addition, we are using a cement type with a lower environmental impact than is normal in the precast industry. By producing the girders ourselves, we expect an ECI reduction of 18%. We will conduct another evaluation, which will also look at the actual ECI reduction.
In 2023, we also committed to an ECI reduction in the Sea & Delta Performance Contract, Oosterscheldekering (PCZD-OSK) and Basic Maintenance Contract South Netherlands - Lot Midden projects. In the case of PCZD-OSK, subcontractors’ equipment and commuting are also included in the scope of the ECI, which ensures broader chain responsibility. For the Sea & Delta performance contract, South in the Ghent-Terneuzen canal, we installed a plastic trap. In cooperation with the Clear Rivers organisation, we have installed a plastic catcher and the captured waste is being analysed. The initial analysis of the waste shows that the captured plastic consists mainly of nurdles (small plastic granules).
Bio-based building materials from hemp fibre
In 2023, we announced that this year we plan to start a trial in Friesland to grow and apply bio-based building materials made from hemp fibre. The aim is to use hemp for the first time as insulation material in around 20 Horizon homes. We not only want to make our housing concepts more sustainable, but also look at whether the cultivation of these raw materials can serve as a business model in the agricultural sector. For this trial, we started a cooperation with a farmer from the municipality of De Fryske Marren and the company GreenInclusive. The hemp will be cultivated on more than 6.5 hectares of agricultural land owned by Heijmans. Together with GreenInclusive and the tenant farmer, we looked at whether it was possible to cultivate natural raw materials as part of his business. The farmer himself is curious about the sustainable crop and wants to integrate its cultivation in his business in the coming year. One important aspect was the guaranteed purchase of the 6.5 hectares of raw materials. This was made possible by the cooperation between Heijmans and GreenInclusive.
GreenInclusive will take care of cultivation supervision and the processing of the raw materials into bio-based building materials, such as insulation or sheet material. Heijmans will purchase the end products for its own Horizon housing concept. Those houses will be manufactured in nearby Heerenveen in Heijmans’ timber-frame house production plant.