The construction sector accounts for one-fifth of Sweden's plastic use and greenhouse gas emissions. We want to increase the understanding of plastic products in buildings and how these can be upgraded to circular alternatives. By circular plastic products we refer to reuse of products and products with recycled or bio-based content. In addition, the products should be prepared for future reuse and/or recycling. If impossible, a product with bio-based, virgin content may be the most climate-smart alternative. An important part of the project is to test circular solutions in collaboration with producers and propose how requirements could be set. By disseminating the knowledge, we want to drive the circular transformation of the construction sector. The goal is to accelerate product development to increase the circularity of plastic building products and thereby reducing climate impact. Through participating parties, the project is anchored in the entire building industry's value chain.