ANALYSIS OF THE EARTH CONSTRUCTION’S THERMAL BEHAVIOR – IN SITU MEASUREMENT AND EVALUATION OF THERMAL PERFORMANCE OF THREE RAMMED EARTH CASE STUDIES

Abstract

The emergence of the new paradigm of sustainable construction related to the concern of excessive energy consumption of our society, led to the investigation of techniques, materials and construction solutions that could causes less environmental impact. Consequently, the interest given to ancient techniques that dealt with earth constructive solutions aroused, which has captivated the interest of architects, builders and people in general. Although this type of material is associated to a less dignified and poor construction, the search for modern expression in new buildings’ design has shown the physical and plastic potential of the usage of earth in modern architecture.

However, the regulation of the constructions’ minimum requirements related to materials’ mechanical strength and thermal performance (such as the Portuguese Thermal Building Regulation- RCCTE), has been one of the biggest obstacles in spreading and growing the application of this technique. This study intends to increase the knowledge of the thermal behavior of this type of construction.

In this article, the results of in situ measurement campaigns, carried out during the summer and winter periods, are presented. They were performed on three different single-family dwellings located in Abrantes, Portugal. These dwellings were built using the rammed-earth technique, each one having walls with 50-55 cms of thickness. Several experimental measurements were conducted in order to evaluate the rammed-earth wall thermal behavior, such as: the incident global radiation on vertical plane of the facade; indoor and outdoor environment temperatures and moisture; indoor and outdoor surfaces wall temperatures; and heat flows. The experimental results revealed a large thermal inertia of the walls, which led to low indoor temperatures in both seasons. The results demonstrate the need to improve the thermal conductivity of the earth in order to meet the minimum requirements imposed by the Building Regulations.