Our OP-Zuid project LEEF focuses on innovative optical coatings for energy-efficient windows and BIPV. Within the project we are developing thermochromic infrared (IR) regulating glass coatings for smart heat management in windows. To this end, OP-Zuid project LEEF builds on the knowledge within Interreg project EnergyEfficiency (2016-2019) in the field of heat-regulating multifunctional coatings in buildings. Furthermore, we are developing multifunctional coatings for BIPV cover glass to realize coloration without major impacting cell efficiencies and self-cleaning properties. The thermochromic smart window will be demonstrated on pilot scale in a test building and solar panels with our new multifunctional coating will be installed in occupied buildings at the A2 travers in Maastricht. The LEEF technologies reduce the energy consumption in buildings via smart solar heat regulating windows and increase the freedom-of-design and reduce maintenance costs in BIPV, which increases the implementation rate. In this way, LEEF makes a major contribution to the goal of an energy and climate-neutral built environment by 2050.