Towards zero energy buildings

Key features of the Finnish energy policy are improved energy efficiency and increased use of renewable energy sources. To achieve a sustainable shift in the energy system, a target set by the authorities, both energy savings and increased use of low-pollution energy sources are therefore priority areas. Building low-energy buildings, characterized by lower thermal energy demand than new buildings with ordinary energy standard, is in accordance with the declared national aim of reducing energy use. However, the use of electricity and domestic hot water in residential buildings will be of more importance to CO 2 emissions in the future. Presently, the share of renewable energy used in the built environment is very modest. Both at national and international level, the targets for energy efficiency and share of renewable energy production imply a steep increase of intermittent renewable energy. The ambition in sustainable development in built environment is to enable the utilization of the full potential of renewable energy of the energy demand on district level. Such a large share of renewable energy with present day technology has a number of challenges. The renewable energy supply such as solar or wind energy has a fluctuating character, which is obviously problematic to the demand side: energy needs are usually rather constant or not at the same cycle as the supply. In addition the peak supply from renewable energies can be much higher that demand and the excess energy cannot be stored. Especially in northern climate, the space needed for local renewable production might become disproportionately large (area of collectors, etc.). Furthermore, the location of the building/district is not always suitable for utilization of some renewable sources. The aim of the study is to find out most efficient way to construct close to zero energy building