Nothing in the attic goes to waste

A more circular economy goes hand in hand with a more sustainable use of materials and products around us, but also of energy.

That is why the city of Roeselare, in collaboration with Test Aankoop, wants to give its residents the opportunity to participate in a group buy for roof and cavity wall insulation. In order to draw extra attention to this action and to stimulate as many people as possible, we organised the attic clearing action Zolderdebolder.

The idea was simple: everyone who took part in the group purchase to insulate their roof received help from the city to clear out their attic.

All discarded materials were collected free of charge and separated into reusable and non-reusable. Reusable materials were given a second life on a 'Geefplein' or were upcycled. For the 'Geefplein', we developed a method whereby certain target groups were given priority. In this way, the reusable material reached the people who benefited most from it.

All these actions not only stimulated the group buy for insulation, but also gave the residents extra insight into the concept of the circular economy.

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Stad Roeselare

Partners VOC Opstap, Buurt en Co vzw, MIROM, De Kringwinkel Midwest, ONBETAALBAAR, Test Aankoop



  1. Regarding group purchasing, 38% of the total number of registrations in Flanders came from Roeselare via Test Aankoop. In the end, 40 roofs were insulated. This is a very good figure for energy-saving works.
  2. Thanks to the clean-up campaign, it was possible to reach a more difficult target audience for roof insulation, namely older customers or customers for whom the hassle of insulation, such as clearing out the attic, was too big an obstacle.
  3. When registering for the group buy, 27 residents of Roeselare were interested in the clean-up campaign. In the end, 9 clearances took place. This means that almost a quarter made use of the offer from the project Zolderdebolder.
  4. About half of all the material coming from the attics was still re-usable. Half of it found a new owner via the 'Geefplein', the other half ended up in a recycled goods shop. Non-reusable materials were sorted and reprocessed into raw materials or used as fuel by a waste processing company. The heat that was released was collected in a heat network.


  1. The project made us realise how much reusable material is lying around unused in people's homes. We found that, in order to save time and effort, people prefer to take everything to the recycling park when they are cleaning up, without first looking at what can be reused. We need to look for ways to encourage our residents to get their unused material to a new user.
  2. We have noticed that group purchases for energy-saving measures have become a bit of a habit. Through this project, we have discovered the positive effect of 'nudging', i.e. promoting certain behaviour by means of a certain action, for instance. One in four of those who had insulation work done through the group buy made use of the attic clearing action.
  3. Sometimes there was still disbelief about the free clean-up campaign. This indicates that quite a few people are not yet completely familiar with nudging. It will be important to focus on this when using this method in other domains in the future.
  4. The participants became aware that there is still a lot of reusable material languishing in their attic. We made people realise that not all discarded material is just waste, and that material that is no longer useful for them can still be useful for someone else.
40 roof insulations
9 attic clearances
4.294 kg of material collected
25% found a new user