In France, the existing building stock is remarkable for its diversity... After several centuries of an architecture that took into account the bioclimatic environment, using mainly local resources and materials, an industrialized architecture emerged, subject mainly to economic and urban constraints, employing new materials with very different thermo-physical properties.
This existing building stock is also marked by the oil shocks of the 1970s and the introduction of the first thermal regulations, which encouraged the production of more hermetically sealed, ventilated, artificially heated and lit buildings.
As a result, millions of existing buildings have been designed using a wide variety of methods and techniques. Against this backdrop, the energy performance of existing buildings is often poorly understood, and remains difficult to characterize.
In this article, educational buildings and older buildings are presented as case studies to show how the complexity of characterizing the energy performance of existing buildings can be better understood.