ABSTRACT
Introduction The challenge that building stock poses in the face of climate change urges building professionals in many countries across the globe to renovate existing stock with sustainability and energy efficiency in mind. Around 30 to 40 per cent of worldwide primary energy is used in buildings (UNEP, 2007) and space heating and domestic hot water services are taking up a considerable share of almost 75 per cent (WWF, 2008). It is expected that an existing home requires four times as much energy for heat as does a new home (DTI, 2007). One of the few industrialized countries in which CO2 emissions have been reduced since 1990 is Germany. A considerable share of savings made in Germany in recent years can be attributed to the national climate protection programme under which credit programmes were launched in October 2000 for renovating existing buildings. Along with other policies, these programmes will allow Germany to meet a 54 per cent reduction in CO2 emissions of 1990 levels by the year 2030. The overall aim is to reduce the CO2 emissions from 1990 to 2050 by 80 per cent. The KfW CO2 Building Rehabilitation Programme proved to be Germany’s most effective element of the national climate protection programme for existing housing stock. The two most effective components within this programme are (UBA, 2008):
1 retrofitted external insulation of existing buildings; 2 replacement of boilers with new high-efficiency
heating systems.
