Summer thermal

Summer thermal
DateProject completed
Timber frame construction meets energy, acoustic, mechanical, reliability, durability, fire and environmental requirements. However, this construction system is penalised in terms of thermal comfort in summer, due to its inertia, which is considered to be light or very light by the regulations.

The project, funded by CODIFAB, FBF and DHUP, proposes a method for the calculation of inertia in thermal regulations, with the emphasis on parameters specific to the timber frame system.

Regulatory calculation tools: Real impact of certain phenomena and parameters of wood-frame construction on summer comfort

The main objective of the “Thermique d’Eté Bois” project was to verify that the regulatory calculation tools are appropriate for wood-frame buildings. The project, carried out in partnership with the CSTB, CEREMA and NOBATEK/INEF4, made it possible to study the real impact of certain phenomena and parameters specific to timber-frame construction on summer comfort, particularly on the current and future indicators of the thermal regulations.

The first step of the project was to evaluate the impact of the input data on the result of the regulatory calculation for wood-frame constructions. Based on a state of the art of wood-frame construction systems, it was necessary to define the typical configurations of wood-frame construction, and then to carry out a sensitivity study according to the different methods of the Th-Bat rules.

Study of three phenomena by modelling

In a second phase, the project focused on the development of methods to improve the consideration of the specificities of timber frame construction. For this purpose, the following three phenomena were studied by modelling:

  • Hygroscopic inertia,
  • The inclusion of thermal bridges in the inertial calculation,
  • The impact of the ventilated air gap behind the cladding.

The results of the project were presented to the Th-Bât commission at the beginning of 2019 with the aim of contributing to a better consideration of the specificities of wood-frame construction through the revision of certain calculation rules of RT2012.

In addition, methodological sheets on integrated thermal bridges and the ventilated air gap have been drawn up and are available to those involved in the sector and to design offices on request. These sheets summarise the methods developed and offer step-by-step guidance for applying them and using them for regulatory calculations in compliant software.