Reale Trends des spezifischen Energieverbrauchs und repräsentativer Wohnraumtemperierung bei steigendem Modernisierungsgrad im Wohnungsbestand

Trends of the specific energy consumption and actual living room temperatures in view of an increasing degree of modernisation of the building stock.

Room-temperatures and heat-radiator-performance have statistically poorly been investigated yet. Additional temperature comfort and air ventilation losses seem to rise inside modern building enclosures. The present study refers to more than 1 million field measurements derived from electronical heat cost allocators (EHCA) within buildings of documented energy efficiency standard. We see a trend of 1 to 1,5 K rising median room-temperatures between old building standards (before 1977) and the modern EnEV2002 standard. Temperature increase is almost double as high within actually unheated-compared to actively heated rooms. The fraction of active heat radiators at any time during winter is decreasing from above 40 % to close below 30 %. At the same time the room temperatures are more homogenously distributed in modern buildings. The relative energy transfer appears well correlated to the yearly integral energy consumption (DIN EN 834) of the EHCA and also to the area-specific energy-ratings calculated from the primary energy consumption.
Energy ratings and temperature measurements confirm that the average actual energy consumption starting from the oldest buildings (before 1977) up to the modern EnEV 02 standard has only been reduced by little less than 50 %. An extrapolated trend ahead from 2002 to EnEV 09 forecasts, that the future energy consumption (EnEV 2009 and further) will probably and clearly exceed the official claims concerning theoretical energy needs: Specific heat energy consumption above 50 kWh/(m²a), plus at least 25 to 30 kWh/(m²a) for domestic water heating, will remain the rule, indefinitely. On the other hand, potentially negative and unintentional influence of individual user behaviour on the integral energy consumption will further rise, because the energy-release into the living environment gets more and more disconnected from the human perception (bio-feedback). Almost one fifth of the energy-release has already moved into a region further above average energy-release-values in the course of EnEV 2002 standard and this trend will continue with EnEV 2009 an its followers. Highly effective building enclosures apparently do not justify a more carefree user attitude interacting with the flat heating. Concerning upcoming new unattended heat sinks one should consider to develop new assisting tools.