Optoppen: building up with timber

*Launched in November 2024: A new platform and tool for building owners, investors and cities - easily analysing the potential for building up with timber* From 2020 to 2060, the world is expected to add 241 billion m2 of new floor area to the global building stock — equal to a Paris to the world every week for 40 years.* We need to provide the additional built space we need using methods and materials that respect our carbon boundaries. Enter ‘Optoppen’ – the Dutch term for building on top of existing structures – a practical solution that avoids carbon-intensive demolition and rebuilding. Adding timber extensions to the tops of buildings increases floorspace in a way that minimises construction emission, using the structural capacity they have to spare. Throughout 2024, European network Built by Nature funded a consortium of diverse partners led by Whitby Wood and including Mule Studio, New Urban Networks EU, Holland Houtland, Institute for Advanced Architecture of Catalonia, Creative City Solutions, and Rising Tide, to develop an open-source knowledge and technical information platform to increase our understanding of vertical extension using mass timber. www.optoppen.org *UN Environment programme, March 2024