Our society demands the sustainability of the built environment and housing stock. A clean, flexible and healthy living environment for everyone and a future-proof place to live, work, learn and recreate. Ambitious national and regional targets, such as making 1.5 million existing homes sustainable by 2030 and a complete circular construction by 2030, are leading in this respect. This requires an effective transition to a future-proof built environment and a vital building economy. This requires an efficient and area-oriented approach at district level in which sustainability and circularity are central.In the North of the Netherlands, the right momentum is present to make the transition to a clean, flexible and healthy living environment for everyone. The region has relevant knowledge, a healthy entrepreneurial spirit and a solid infrastructure to support innovation. In addition to ambitious business, the northern provinces have progressive public actors with local sustainability goals. Several initiatives such as Building, DrentheWoontCirculair, Vereniging Circulair Fryslan underline the transition potential. A regional challenge is to strengthen the innovative power of action, translating ideas from small and medium-sized enterprises (SMEs) into practical applications. The innovation ecosystem has been strengthened in recent years, resulting in more innovative SMEs in the Northern Netherlands. The response to societal challenges (e.g. sustainability) and the valorisation of innovations by SMEs is still limited. The closure on the existing innovation-supporting ecosystem is missing in the North of the Netherlands: a physical location to valorise and integrate sustainable circular building solutions and market innovations in an accelerated, efficient and flexible manner into commercial and social success from housing to district level. Developing builder Van Wijnen, in collaboration with partners, takes the initiative to invest in the realisation of an open innovation environment for the Built (G) Environment (O) at district level (W): the GOW! testing ground. An on-site and online environment for market-oriented co-creation of individual/integral (circular) solutions aimed at speeding up and cost efficient sustainability of the built environment in the North of the Netherlands on a large scale. Van Wijnen wants to build on the existing innovation ecosystem in the North Netherlands by building a bridge to practical applications with valorisation and integrality as a spearhead. The testing ground is distinctive and complementary to existing initiatives. The GOW! Test garden offers: — Open-innovation on-site and online environment — 3 pop-up labs in the district and 1 GOW! platform- Valorisation services — 3 packages: customer experience, business model, integrated neighbourhood solution — network integration — cross-sector collaboration and connecting labs/initiatives. The GOW! Testing ground is innovative and complementary to operational initiatives in (North) Netherlands within the future-proof and circular building segment. The challenges for (circular and future-proof) housing are huge and the need for breakthrough innovation and sustainable transition is huge. Full-scale cross-home initiatives will be dealt with in a limited way. In addition, the tests often take place in local sites within a fixed space in the existing laboratory or have a more one-time character in an operational (neighborhood) environment. All initiatives aim to connect to the market and speed up market transitions. While customers and end-users are involved in technology development, there is less development from a specific market demand. The focus is mainly on support in the TRL phase 3-5, stimulating technological innovation and less on market innovation and creating social and economic added value (valorisation) at TRL level 6-7 and scaling up to TRL 8-9.There has been deliberately chosen for testing in and together with the district instead of a fixed location of Van Wijnen to increase its open and independent character. The pop-up testing ground thus fits in with the dynamics and challenges in the district. By focusing on the needs of stakeholders in the district, the agenda of the testing ground is formed. This is in contrast to a fixed physical location where the lead partner is mainly steering. Van Wijnen has extensive experience in setting up model homes in the district and using living labs, where sustainability solutions are developed and tested together with SMEs. The control of the testing ground is coordinated from the Van Wijnen branch in Heerenveen. After 3-4 years, the lab will be moved to another district and new challenges will be addressed. Diversity and wider involvement will therefore be possible within a continuous cyclical trajectory.