The thermal performance of Thin Reflective Products is expressed exclusively in terms of thermal resistance R

CSTB reminds private individuals and professionals that the thermal performance of insulating materials is expressed exclusively in the form of a thermal resistance R measured in units of the IS measurement system (m2K/W), excluding all other units.

In a press release on November 7, 2007, the Minister of Ecology, Planning and Sustainable Development (DGUHC) repeated that this thermal resistance R should be the only measurement used for application of the regulations so as to guarantee to occupants that they are receiving the performance that they are entitled to expect when buildings are designed and constructed in accordance with good practice.

In the special case of the thin reflective products, the thermal resistance R may be determined within the framework of a European Technical Approval or a Technical Assessment.

A Technical Assessment has now been issued for eight products of this nature. These assessments are available on CSTB's internet site. A European Technical Approval is currently being investigated for the purposes of CE marking for two of these products. The default value of the thermal resistance R to be used for thin reflective products without a European Technical Approval or a Technical Assessment is given by the THBât application rules, according to the regulatory provisions summarized by the Ministry (see document to be downloaded).