The calculation method for the 2012 Thermal Regulations - General points

Successive French thermal regulations, from RT 88 to the current RT 2012, have seen a steady increase in the energy consumption requirements for new buildings. This increase in requirements is naturally accompanied by an increase in the complexity of the calculations needed to assess them.

The sheer scale of the calculations, and the resulting multiplication of parameters and input data, make it difficult to take an intuitive, or even physical, approach to improving energy efficiency in the regulatory sense. This is why a good understanding of the intricacies of the calculations carried out can pave the way for further optimization of the regulatory study.

The aim is for everyone involved in the building design and construction process to find the information they need to understand the "spirit" and particularities of the method. This will enable them to deal more effectively with tricky points and reduce bottlenecks.

The aim of this article is to explain the calculation method in its entirety, as well as general concepts such as taking the building environment into account. Other specific aspects are covered in a more detailed article [C 8 111] .

All the information presented is based on an in-depth study of the regulatory texts (decrees, orders), their appendices detailing the calculation methods, and certain standards cited in the texts themselves. A reconstruction of the primary modeling (RC method) of the simulation used has also helped to clarify the foundations of the method.

At the end of the article, readers will find a glossary summarizing the usual abbreviations used.