Lightweight composite timber façade wall with improved thermal response

For the construction of modern energy-efficient buildings, lightweight construction is becoming very popular among designers. EU legislation encourages such design, especially if wood, as a sustainable material, is used. However, lightweight building envelope construction, in general, exhibits poor dynamic thermal properties, which are particularly pronounced in prefabricated metal walls and thin wooden or composite building panels, such as door fillers or opaque parts (parapets) of prefabricated walls with the glazing of the skeleton-built buildings. The aim of this research was the development of a composite timber façade wall, which will not exceed the thickness of building elements, such as doors and windows, and will meet the requirements of energy efficiency and have improved dynamic thermal properties. The composite timber building element with a thickness of 68 mm, which includes two layers of advanced technologies: vacuum insulation panel (VIP) and phase change material (PCM), was developed and optimized. The optimization included a parametric study on VIP and PCM panels' position in the thin, lightweight building wall. The research has shown that dynamic thermal properties comparable to the heavyweight building envelope constructions (time lag of the heat wave up to 12 h) can be achieved; moreover, the thermal transmittance is considerably reduced.