High performance precast external walls for cold climate by a multi-criteria methodology

Nowadays, the design of Zero Energy Buildings requires a technology of light multi-layered walls and the envelope represents a key element to reach high level of thermal behaviour and indoor comfort. This paper illustrates a method based on a multi-criteria analysis for the design of energy-efficient precast walls in the cold climate. It encourages the use of eco-friendly building materials and local materials, in accordance with the directions of the Building Sustainable Protocols, like LEED and Itaca. The designed methodology involves the use of MatLab rel.7.0 for the computational procedure and the modeFRONTIER rel.4.3 optimization tool to evaluate the dynamic behaviour of the building components and to obtain a multitude of high efficiency configurations. The optimization has been performed in terms of steady thermal transmittance, periodic thermal transmittance, decrement factor, time shift, areal heat capacity, thermal admittance, surface mass, thickness, supply and installation costs and ecofriendly score. Furthermore, hygro-thermal and acoustic check have been evaluated for three walls, selected between the most efficient. The walls present no interstitial condensation. The results highlights that it is possible to rich high efficiency precast walls also by thin and ultra-thin thicknesses.