What’s a SUSTAINABLE EXHIBITION?This installation/exhibition aims to provide a possible answer to this question, as well as to promote dialogue and integration between cultural, aesthetic values and environmental values. Modular elements were used In the assembly of the installation, with no cuts, by simply placing them and thus allowing a reduction of waste during assembly and their full utilization and/or return to retail companies/manufacturers at the end of the fair. The trees exposed represent a possible way to compensate GHG emissions from an event that lasts only 4 days, in a time horizon of 30 years, illustrating the significant environmental impacts of our activities, challenging companies and visitors to participate actively in offsetting their emissions while contributing to the creation of new public green spaces, a legacy to future generations. The aim is also to publicize the work of OASRN - Northern Chapter of Portuguese Order of Architects, during the triennium 2007-2010, in the process of building its new headquarters and North 41º - Center for Architecture, Creativity and Sustainability and In short, We propose a beautiful, strong and sustainable installation.