Another example can be found in the center of Maastricht. Can you imagine a bookstore in a church? Or even a hotel? The Kruisherenhotel is composed of a former Gothic church, which now houses the reception area and several hotel facilities, including conference rooms, a library, a boutique, a restaurant, and a wine bar, and of a monastery converted to 60 hotel rooms. The architectural firm SATIJNplus Architecten managed to place all the functions needed to the existing space, almost without touching the original construction.
Kruisherenhotel Maastricht lobby, picture by Tripadvisor
This last example is in terms of environmental impact the best to be done. Instead of building a new building, an existing and unused building is converted for a new use.
The only even better option is doing nothing. Nothing costs no energy, and no material is used. What does it mean for the construction sector in practice? To keep in use what we have as long as possible, to maintain, repair, take care of the buildings. This where it comes to the users and their role in the circular economy. The users are crucial to extend the life of the buildings and their components, to allow to explore the full potential given by the durability of the building materials.
This may seem as a conclusion, but in a circular economy, not even a conclusion can be linear. Doing nothing saves materials, but does it necesarrily save energy? The total energy used by a building is mainly due to the energy embedded in its materials, and the energy used to keep the comfort in the use phase. If a retrofit manages to save more energy, than it is embedded in the materials and technologies needed for the renovation, it makes sense. Concepts like using resused or recycled materials keep the embedded energy low, while passive design strategies such as insulation, shading or thermal inertia, as well as efficient technologies decrease the operational energy.