A modifiable structural system: Feasibility study, screening of trends and predicted future needs

The purpose of a modifiable structural system is to make the structure adaptable to future needs of the building. For example, if small apartments are merged into larger apartments, apartments are transformed into office space or other types of transformations that requires new openings in the building structure.
The initial concept of the modifiable structural system in this project is to design prefabricated concrete walls with flexible zones, which can be cut out without or with very little further strengthening of the structure. The wall element consists of concrete and reinforcement, but the production should allow for different types of concrete in the structural zone and the flexible zone to enable the use of low strength concrete in the flexible zone with a lower CO₂ footprint. The aim of this report is to investigate if there is a need for a modifiable structural system in the market and if the initial concept behind the system makes sense to further develop and analyze throughout the PhD project. If not, adjustments to the concept needs to be made. Furthermore, the report provides some valuable background knowledge about some aspects of the building sector, which helps contextualizing the project. To limit the framework of the report, the focus of the report is on housing in the Danish market. Throughout the report the following is investigated. The historical development within housing and current trends are outlined, to see if the needs and types of housing has changed over time and to see if there is a clear direction that makes us able to predict the future needs of housing, or if we do need flexible solutions that helps buildings adapt for changes. Furthermore, the development within renovation of buildings is investigated, to see if the tendency for renovation compared to demolish and build new is increasing and which parameters that drives the decision for renovation or transforming a building. Some of the drivers for using the modifiable system are the short-term and long-term environmental impact and therefore the incentives that makes the construction industry focus on the environment and sustainability is outlined in the report. An alternative to the use of concrete in the flexible zone could be to make the flexible zone of some sort of lightweight material. Therefore, it is investigated what the technical requirements in terms of sound insulation and fire insulation are for a wall between two dwellings, to see if there are advantages of using concrete compared to a lightweight material. At the end, the flexibility of building structures is further investigated. This is done by looking at previous industrial building systems that are made with a focus on flexibility, to see if we can learn something from them. Furthermore, some cases of concrete walls that are prepared with flexible zones are shown, and different stakeholders from the industry are interviewed to get their view is on flexibility in buildings and what they think about the concept of the modifiable structural system from this project. The report and the process that led to the result, supports the need for and the initial ideas behind the concept of the modifiable structural system made of prefabricated concrete elements. It also provides a good background knowledge for why it is needed, which cases it can be used for, how the focus on sustainability in the market can be a driver for implementing the modifiable system, which benefits there are of using concrete in a wall compared to lightweight material, insight in other flexible systems that has been developed through time, and that different stakeholders in general like the concept, both in terms of the flexibility it provides and the potential lower CO₂ footprint.