Background and aim. Developing timber buildings suitable for deconstruction, reuse, and adaptability in practice is challenging and complex. The project “Design for the Future - Reuse of Timber Buildings in a Circular Economy” developed two concept buildings to be reused with preserved functionality. Focus was on environmental benefits and was obtained through collaboration within the circular value chain and according to real estate developers’ requirements. One building featured industrially manufactured volumes designed to be relocated and rebuilt. The other was an adaptable building with planar elements, designed to be flexible, relocated and vertically extended with two added floors. Methods and Data. The concept method, a co-creation process, was used that involved possible scenarios, construction, deconstruction, reconstruction, waste management and estimation of reusability. The method SimFORCE, Simulation for Future Oriented Reuse and Circular Economy, was developed. Evaluation of reusability and preserved functionality was conducted in cooperation with expert groups. The climate reduction potential of reuse was analysed using Life Cycle Assessments. Findings. SimFORCE helps identify whether structures are designed for deconstruction or need improvement. Further, the results were useful in preparing and writing deconstruction and reconstruction guides. Climate calculations show a significant reduction in environmental impact when buildings are reused. Theoretical/Practical/Societal Implications. With SimFORCE, two timber buildings were demonstrated as possibly being reusable with preserved functionality (structural, acoustics, fire resistance, etc.) with a considerably reduced climate impact. Assessments were based on profound knowledge and experiences of the building systems, deconstruction and testing. The actual buildings have not been deconstructed and rebuilt.