Energy Efficient Retrofit Guidebook International Overview of Current Practices by Retrofit HUB Training Activities by Retrofit HUB Energy Efficient Renovations in Practice Training Series Energy Renovation of Multifamily Buildings – Obstacles, Solutions and Opportunities Hungary Green Building Council (HuGBC) Polish Green Building Council (PLGBC) Croatia Green Building Council Project Retrofit HUB: Training Activities Renovation and Retrofitting of Old Buildings in Times of Climate Crisis