Forty years of regulations on the thermal performance of the building envelope in Europe: Achievements, perspectives and challenges

The necessity to improve the buildings' energy behaviour became peremptory as a consequence of the two oil crises in the 1970’s, and was expressed primarily in the effort to reduce the demand for heating, ventilation and air-conditioning, whilst improving the rather modest indoor environmental conditions standards of that time. It has been quite a long way from those days to the Zero and Nearly Zero Energy Buildings required by contemporary regulations. The way has been paved by intensified, systematic developments, of an advanced, and experimentally well validated, interdisciplinary theoretical background, by its incorporation in the syllabi of most engineering and architectural university courses and by a legislative framework that transcended national regulations and standards offering European directives and harmonized European standards.There is a bi-directional relationship between the aforementioned development and the progress made in the field of building materials and systems. The successive, ever tightening regulations act as driving forces for the development of effective insulating materials, airtight buildings and smart façades, not to mention the HVAC and predictive BAC systems. It is the availability of those building elements and materials that enables the implementation of ambitious and innovative designs, ensuring that fewer limitations are imposed on the architects’ work.After all, one has to keep in mind that forty years after the implementation of the first thermal insulation regulations and more than ten years after the establishment of the first Energy Performance of Buildings Directive, thermal loads still account for almost two third of the buildings’ loads. The further reduction of those loads becomes a more challenging task, the lower the loads become in absolute terms; it is this challenge that calls for new, more advanced building materials and elements but also for a more sophisticated, integrated regulatory approach.