Guarded hot box

Photo: Florence Joubert

The CSTB installed the guarded hot box in 2016 at its facility in Marne-La-Vallée, in a 290 square-meter space.

This system assesses the thermal performance of opaque and glazed walls, at full scale and accommodates configurations representative of the way they will actually be used in buildings. Coupled with digital simulation, the results can be used to make usage recommendations for professionals.

The guarded hot box provides precise measurements that can guide the development of new insulation products and techniques, in a context of stricter energy requirements, with a long-term guarantee of in situ performance.

What's a guarded hot box? In this set-up, the wall to be tested is positioned between two ambient conditions: one hot and one cold. Measurements are taken of the dissipated heating power that maintains a constant temperature gradient through the wall. With this information, i.e. the dissipated power and the temperature difference between the two ambient conditions, the experts can deduce the thermal performance of the wall. They also analyze the thermal performance of the installed product, or the impact of its use.

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