An old nursery building in Ostrava was changed into a multi-purpose low-energy house for children, their teachers and families using solar energy, a biomass boiler for wood chips, and an underground heat exchanger for heat recovery. Although the building area increased during refurbishment, fuel consumption decreased. The annual energy consumption for heating decreased from 220 kWh/m2 to 46 kWh/m2, and energy is 100% supplied from renewable energy (LG Action, 2010).