Optoppen project gets under way

December 2023
Whitby Wood is leading the new Built by Nature-funded consortium — Optoppen — set up to look at the potential of timber-based vertical building extensions in European cities. The aim of the project is to develop an open-source knowledge and technical information platform that will help raise awareness and understanding of how to unlock building floor area, create new carbon stores and keep construction emissions to a minimum.

Optoppen, or ‘topping up’, increases the useable space in a building through lightweight roof extensions, using timber in the process to create carbon sinks on top of cities, contributing to urban decarbonisation targets and to densification strategies. With Europe’s cities facing housing crises, Optoppen, as an alternative to demolishing a structure to build newer and bigger, saves existing embodied carbon while enlarging a building’s usable area with a low-carbon material that additionally stores biogenic carbon.

Kelly Harrison, Director at Whitby Wood and the project lead comments, “The construction industry needs to drastically decrease its impact on our climate, and there are ways it can do that with the technologies and resources we have today.”


Central to the project is an interactive website that will enable city planners and asset owners to quickly understand the vertical extension potential of their buildings, providing high-level structural assessments and reporting the potential floor area that could be created, as well as carbon stored in the extension’s mass timber. Research will focus on common building types in European cities — focusing on the UK, the Netherlands and Spain — with estimations available at building and city levels.

Built by Nature has generously awarded €211,000 to the year-long project. Built by Nature is a network and grant-making fund — backed by philanthropic funding — with a mission to accelerate the timber building transformation in Europe, and a vision for a built environment that works in unison with nature.

Optoppen is a UK, Dutch and Spanish consortium
The implementing partners ….
Whitby Wood
Creative City Solutions
Holland Houtland
Institute for Advanced Architecture of Catalonia
Mule Studio
New Urban Networks EU
Rising Tide