Since 1994 he has been working as a member of design studios of leading global architecture, design, planning and consulting firms as Perkins&Will and Gensler in Chicago, Los Angeles, London and Amsterdam.

 In addition to that, in 2001 Greg founded zero-Lab design studio in Amsterdam focusing on residential market, designing projects throughout the Netherlands and building custom designed furniture in Poland.

 In 2008, as an attempt to combine both, commercial and residential interests and expertise, Greg started Lozinski Architecten. The new studio is based in Amsterdam, focused on local work, often for global clients.