Test facilities

Thorough knowledge of the physical characteristics of insulation products contributes to the development of energy-efficient buildings. In the hygrothermal analysis laboratory in Marne-la-Vallée, the CSTB performs tests to characterize the durability and energy efficiency of insulation products and systems. The laboratory has substantial capabilities for subjecting products to precise and varied temperatures and humidity levels. As part of its consulting, assessment and certification services, this laboratory performs tests in accordance with current standards, with COFRAC No. 1-0300 accreditation (scope available on www.cofrac.fr). It is one of the pilot laboratories involved in ACERMI (Association for the CERtification of Insulation materials) certification.

The guarded hot box

This CSTB laboratory can measure the thickness and density of an insulation material or system. For bulk insulation materials in particular, the laboratory has an insulation blowing and insufflation machine. It simulates use of a material and measures the density of the applied product.
This laboratory can also characterize mechanical strength, compaction, thermal resistance and moisture levels of insulation products and systems.

Mechanical strength

The laboratory has equipment (presses, creep testing machines) for measuring the mechanical performance of products. In accordance with reference documents (Unified Technical Documents , certification benchmarks), measurements of tensile, shearing and compression resistance are performed to determine the appropriate uses of products based on the expected constraints once installed in the building.


The final thickness of installed bulk products has a direct impact on their insulation capabilities. The laboratory performs compaction tests on bulk samples subjected to specific temperature and humidity conditions. These tests predict product performance over time.

Thermal resistance

The laboratory measures the thermal resistance of insulation materials using a battery of guarded hot plate apparatuses and flow meters. Some of these apparatuses are equipped with robot loaders that operate 24 hours a day, reducing the total processing period. In addition, fully-configurable equipment adjusts to products with special characteristics, such as bio-sourced products.
In 2016, the CSTB will have a guarded hot box apparatus for thermal tests on insulated walls with sizes up to 2 m x 2 m.

Water resistance and water vapor permeance

The performance of insulation products also depends on their water content. Once a product is installed, its performance depends on its ability to store liquid water and allow water vapor to pass. Tests performed by the CSTB can help reduce flaws in products and ensure continued thermal performance in accordance with their intended purposes.

Digital simulations can be performed in addition to laboratory tests. They are carried out on full-scale products and walls to predict hygrothermal properties based on various parameters (intrinsic characteristics of materials, boundary conditions for temperature and humidity, design and wall installation).

To determine the insulation capacity of a reflective product, the emissivity of the external sides must also be measured. The CSTB’s laboratory in Grenoble performs these measurements.