The goal of the project is to make apartment buildings in Denmark more energy efficient by reducing heating energy requirements. The researchers are developing new technologies like integrated PV-roofs and 3-D finishing of façade insulation to achieve this. The aim is to reach Zero Energy Building levels or nearly Zero Energy Building levels. The key findings include the use of insulation, low-energy windows, heat-recovery ventilation, solar hot water, and PV-systems in the renovation process.