Study of thermal behaviour of clay wall facing south

Sustainable development includes socio-economic and environmental targets and concerns all sectors of human activity. The main reasons for green building are to reduce energy consumption, green house gases emission, water use, waste production etc. The choice of materials used for the construction of a building has a direct impact on the environment. A material with a low life-cycle cost (LCC) and high technical performance reduces the impact of the building on the environment. Cob is a traditional material with a low LCC; its thermal performances are studied here and compared with the thermal performances of stone walls and of insulated concrete block walls. A first type of simulation concerns a wall model with an interior temperature set at 19∘C and a second type of simulation concerns a whole building, the wall model is then coupled with a zone model. Three types of buildings are simulated: a conventional building and two efficient buildings. One of the efficient buildings is a block of flats that is part of the European programme CEPHEUS: Salvatierra. The simulations show that, for south-facing walls, the thermal behaviour of a 50-cm-thick cob wall is about the same as that of insulated concrete blocks wall with 7.5 cm of insulation. With a 5-cm-thick insulation added, the thermal behaviour of a south-facing cob wall is then about the same as that of an insulated dense concrete block wall with 15 cm of insulation. Cob is, thus, a traditional material that can be used in modern constructions.