From Single Buildings to Communities and Cities - Energy Efficiency in the Course of Time

For quite a long time energy conservation and energy efficiency were concentrated on a singlebuilding approach. Until 2000 nearly all national building regulations were based on net energybalances (energy needs) comprising transmission losses, ventilation losses, solar gains, internal gains and heating gains. Due to that the development focused on reduced transmission and ventilation losses, and so-called low energy houses or passive houses were designed and demonstrated in pilot projects, at first for new constructions and later on also for refurbishment projects. The national energy performance requirements were based on U-values for building components and then on heating energy needs. With the beginning of the new century, the next step was to integrate the efficiency of the heating, ventilation and domestic hot water systems. Instead of low energy needs, low energy use is now the goal. In most countries the primary energy use (which is the energy use multiplied with primary energy factors dependent on the specific energy source) became the limiting factor in requirements for buildings. Other countries are using the CO2 emissions as a limit. Nowadays, the efficiency of the building systems is equally important as the quality of the building components, and the more building systems are getting integrated (e.g. cooling systems), the more important is their efficiency.On the other hand, strategies and technologies that are applied to many different buildings in thesame area at the same time (like improving the efficiency of the district heating net connected to thesettlement) can be just as efficient regarding the reduction of the energy use and the emissions. Newnational programmes, like the German EnEff:Stadt, concentrate on improving the energy efficiency ofsettlements or communities and are mirrored with European (Concerto) and IEA projects (IEA ECBCS Annex 51 "Energy efficient communities"). The paper gives an overview on the development of energy performance requirements by using Germany as example, national programmes for energy efficient buildings and communities and international (IEA and EU) projects. It presents examples of pilot projects and gives an insight in the work programme of the new IEA Annex 51 on energy efficient communities.