This book focuses on thermal retrofits of homes in Germany, but its findings have
a much wider application than that one country. Germany is one of a number of
northwest European countries that have taken major strides in recent decades to
reduce domestic heating fuel consumption: not only by continually tightening the
thermal standards for new buildings, but also by setting compulsory thermal
standards for existing homes when they are being repaired or renovated. Most
European countries have compulsory thermal standards for the replacement of
windows, doors, roofs, and boilers, but in 2002 Germany took the further step of
extending this to cover the entire outer surface area of the building. If any substantial
repairs or maintenance are being done on the outer walls, basement ceiling,
or loft, these must include insulation to specified standards. Even in the absence of
repairs, any attempt to insulate these areas must reach these standards