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Gypsum boards, kitchen cabinets, insulating wool, parquet floor - an enormous amount of construction materials arrive at building sites wrapped in film plastic.

‘Until now, film plastics have mainly ended up in energy waste, i.e. incineration. It is better than throwing into mixed waste – but not the best solution for the environment’, says Antti Peltokorpi, associate professor of operations management in construction at Aalto University.

Together with doctoral researcher Krishna Chauhan, he studied in a research commissioned by the Ministry of the Environment how much film plastic is produced on average in the construction of apartment blocks.  In Finland, accurate information on the amount of plastic waste has not previously been available, which has made it difficult to arrange recycling at construction sites.

The research involved three concrete building sites and, as a benchmark, one wooden block of flats. Separate collection of film plastic waste had been arranged at the construction sites. For the purposes of the research, the emptying times of the collecting bins and the weight of the waste were recorded and data on how much coloured plastic or dirty plastic was found.

In concrete element buildings, the average amount of film plastic waste was 0.33 kg per gross square. Per apartment it means approximately 26.2 kg. The wooden block of flats produced 3.4 times more film plastic waste than the concrete site. This is because in wooden blocks of flats, the exterior wall elements must also be protected during transport. In the control building, each wooden element was protected separately. If each bundle of wooden elements is protected, 0.7 times more film plastic is used than in the concrete building site.

Dirty and coloured film plastic accounted for an estimated 15–30 per cent of the total amount. Both dirt and the colouring of plastic can make it more difficult to process the material further, says Peltokorpi.

‘When different colours end up in recycled plastic, grey recycled plastic is produced. Colour plastics are used the most because of branding, but better alternatives should be considered.’

Bins in the right place and at the right time

Based on the findings, the researchers developed a modelling tool that allows the developer or the main contractor to assess in advance how much film plastic waste is generated and at what stages of construction. This means that the correct number of recycling bins is available in the right places, at the right time. Film plastic waste is most produced during the indoor manufacturing phase, especially from furniture, windows and doors, tiling, ceilings and for covering.

However, good logistics is not enough, Peltokorpi emphasises.

‘The role of the main contractor is very important. We must consider how the entire construction site organisation, which often includes a large number of subcontractors, can be committed to separate collection.’