Comparative study of hygrothermal performances of strawclay and vertically perforated clay brick buildings

Abstract

The use of bio-based materials in new buildings, such as Straw-Clay (SC), corresponds perfectly to the French goal of 10% share of renewable construction materials by 2020. SC is made up of clay soil, straw and water. However, few laboratory and in situ studies have been undertaken on SC. This paper presents a comparative experimental study of transient hygrothermal behaviour of a SC building to a traditional one with vertically perforated clay bricks (VPB). They are located close in South West of France and have same orientation. Same protocol measurement has been used for both constructions. The envelope is examined through airtightness test with infrared thermography survey. Two walls are monitored for hygrothermal performance. Moreover, RH/T sensors for indoor air have been placed in different rooms. Weather station is installed near the SC building. Data presented in this paper are related to the period between July and October 2013. Unlike SC construction which shows homogeneous surface apparent temperature, VPB building presents thermal bridges located at junctions between the intermediate floor and the walls. In situ monitoring of walls underline that VPB structure has a higher ability to dampen variation of external temperature than SC wall. However, the SC wall acts as a moisture buffer managing the humidity levels within the building and contributing to a healthier environment.