Energy performance and environmental and economic assessment of the platform frame system with compressed straw

In recent years there have been considerable improvements in the energy and environmental performance of buildings, due not only to the creation of building envelopes with a low level of thermal transmittance but also to the use of natural ("green") materials. Construction systems combining a wooden framework with eco-compatible materials represent solutions for a building envelope, which prove effective in reducing both energy needs and the discharge of polluting substances. The principal aim of the present research is to investigate the use of natural waste materials from farm products in the creation of building envelopes. The system described here proposes the use of compressed straw to obtain a layer of insulating material, that may be combined with the use of a wooden shell known as platform frame. The thermo-physical characteristics, energy performance as well as the hygrometric features of the proposed system were tested in various sites. As regard the formation of condensation, the thermo-hygrometric analysis proved the absence of such threat over a period of a whole year in all the different climates observed. A comparison with a similar XLAM system evidenced that the platform frame system lined internally with compressed straw offers a 12% reduction in U thermal transmittance, a 22% improvement in VIE periodic thermal transmittance, and a comparable thermal lag. Moreover, the platform frame system filled with compressed straw allows a cost reduction by 38% compared to the XLAM system. On the whole, the outcomes obtained indicate that the platform frame system with compressed straw offers a suitable alternative to the XLAM system, above all in the case of buildings of two or three stories. (C) 2018 Elsevier B.V. All rights reserved.