Background and relevance

Arnhem plans to build more than 16,000 homes over the next 14 years. A large share of these will be built in three area developments: Rijnpark, Schaapsdrift and Laarkwartier, together accounting for over 1.1 million m² of new construction. Rijnpark is by far the largest: a 70-hectare inner-city industrial estate will become a neighbourhood of around 7,000 homes, requiring the demolition of 180,000 m² of existing buildings. At the same time, the municipality has set ambitious targets. By 2030, Arnhem aims for at least 50% circular construction, and by 2034 the environmental impact and CO₂ emissions per new home must be halved compared to 1990. Traditional construction methods will not get the city there. So the question is how much of the required material is already present in the city, in the buildings that will disappear in the coming years.

Research question

Which building materials will be released through demolition in Arnhem up to 2035, how much of the material demand in Rijnpark, Schaapsdrift and Laarkwartier can they cover, and how much CO₂ can reuse save?

Method

We used the Structural Urban Mining Model. For the city as a whole, we translated demolition forecasts to the period 2025-2035, amounting to roughly 305,000 m² of demolition. Using building profiles, we converted the new construction plans into material quantities and CO₂ impact across three scenarios: business-as-usual, transformation and bio-based. We also mapped the materials in Rijnpark’s public space.

Key insights

• With traditional construction, the three areas together require 1.33 million tonnes of new material, accounting for roughly 0.4 million tonnes of CO₂. More than 1 million tonnes of that is concrete.
• Demolition releases 87.5 kilotonnes of directly reusable building products. Reusing them avoids 15.7 kilotonnes of CO₂, about 3 to 4% of total emissions.
• Concrete provides the bulk, but brick and steel deliver the most climate benefit per kilo. In Rijnpark, more than half of the CO₂ savings come from reused steel, even though it makes up only a small share by weight.
• Each area has its own material profile. The Rijnpark industrial estate mainly yields concrete and steel, while the rest of the city mainly yields brick. In Schaapsdrift, demolition even releases more brick than the new construction needs.
• Bio-based construction reduces CO₂ emissions by 22 to 26% compared to traditional construction.
• Rijnpark’s public space provides another 90+ kilotonnes of asphalt, concrete paving stones and concrete slabs, which can be reused directly in a later phase of the area.

Recommendations

• The Municipality of Arnhem can set a CO₂ budget for its construction programme, give the environmental cost indicator (MKI) heavy weight in tenders, and act as a launching customer for reused materials. Arnhem already requires circular demolition; the gains come from applying it consistently, on every project.
• Developers, architects and contractors can design with what is already there. That means knowing early which materials will become available, assessing with the demolition contractor what can be reused, and adapting design dimensions to, for example, second-hand hollow-core slabs. Prinsenhof in Arnhem shows this works: 594 hollow-core slabs were given a second life there.
• In Rijnpark, the municipality can steer directly because it manages the public space itself. With a materials depot, paving and concrete slabs can move from phase 1 to phase 2, and by aligning the urban design quality plan with this, reuse becomes the starting point.
• Reuse alone will not meet the climate targets. Bio-based construction, renovation and building more compactly deliver more, and belong on the table in every area development.