Urban green infrastructure, including man-made features such as vegetated roofs and walls, produce regulating, provisioning and immaterial ecosystem services such as improvement of microclimate, balancing of hydrological cycle, carbon sequestration, habitat provision, active cooling/insulation, dust filtering, opportunities for gardening and local food production in kitchen gardens, aesthetic improvement, additional green space and recreational services and educational services via e.g. nature paths on the roofs. The area of roofs and walls in cities is enormous, so why not make good use of it for ecosystem services provided by building surfaces. The research programme "Fifth Dimension - vegetated roofs and walls in urban areas" aims to produce high-level scientific and broadly applicable knowledge on optimal vegetated roof solutions in Finland.