A nearly zero-energy building is defined in Article 2 of the Energy Performance of Buildings Directive as “a building that has a very high ener- gy performance. The nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renew- able sources, including energy from renewable sources produced on-site or nearby”. To achieve such net balance of external energy con- sumption, a designer can play on two factors: reduce energy needs of the building and increase the energy production within the system boundaries of the building. Reducing the energy needs, at its turn, can be achieved by improving the performance of the envelope or by using low energy HVAC systems. Using the properties of (structural) concrete, in particular its thermal mass, is a smart and cost effective approach to achieve (near) zero energy buildings.