Circularity was typically not taken into consideration during the design stages for many buildings. Materials are also difficult to reuse for a number of reasons:
A high-grade circularity of building materials is often technically and economically unattractive, and as a result, many materials end up as rubble. This is typically why we see such low-grade reuse of construction waste.
There are different ways to measure circular construction. The recovery rate is an indicator of the ratio of construction and demolition waste, which is prepared for re-use and recycling or subject to material recovery. This includes backfilling: when old concrete is crushed down and used as a filling to support or strengthen structures and groundwork. Backfilling is the lowest level in circular construction and is essentially downcycling.
The circularity rate indicates the share of material recycled (excluding backfilling) and brought back into the cycle, which saves the use of raw materials. This measure outlines the ratio of the circular use of materials (excluding backfilling) to the overall material use.
Enormous amounts of construction waste are brought back into the cycle. According to Eurostat data, almost all construction and demolition waste is recovered in Belgium and the Netherlands. In addition, the recovery rate in the European Union is 89%. But is this high-grade or low-grade circular construction and backfilling?
Recovery rate of construction and demolition waste in 2020
The construction circularity rate (excluding backfilling) isn’t available for the EU. We can, however, take a look at the circular material rate for a bit more insight. This rate is only available for the building product group of concrete, cement, bricks and plaster – but these materials make up the bulk of construction waste.
Although building materials are often difficult to reuse, the circularity rate of concrete, cement bricks and plaster reached 14% in 2021. This means that 14% of material resources used in the industry came from recycled products and recovered materials, saving on the use of primary raw materials.
This is more than 2 percentage points higher than in the EU economy overall – but it now appears to be losing steam. While the circularity rate of all materials in the EU has increased from 10.8% to 11.7% since 2010, the circularity rate of main building materials hasn’t seen any improvement at all.
Development circular material use rate by material type
Circular construction model: entire supply chain involved
In order to change course, begin reducing construction waste and increase the circularity rate, not only contractors but the whole construction value chain must be involved. For circular construction to be as high-grade as possible, the business model of all supply chain partners has to change. Architects and owners have to decide whether old buildings will be reused or demolished, as well as how buildings can be easily converted for new owners.
