ZEMCH 2015 - International Conference Proceedings | Page 575

slightly less than 20% of water and about 40% of burned energy resources. The use of renewable
non-petroleum-based materials, derived from the reusing and recycling of production waste, has
enormous potential to contribute to the reduction of CO2 consumption, and to serve as the primary energy in the production of new construction materials (European Commission 2013).
Hence, reuse and renovation of the pre-existing buildings indicates a key factor for sustainability,
contributing both to reduce the consumption of resources and raw materials, which in most cases have reached only half of their life cycle, and to extend the building’s long-term functionality.
Furthermore, these interventions would offer an alternative to the high costs and consumption
inflicted by the demolition and the reconstruction.
Unfortunately in most 20-50 years old buildings, especially those utilising reinforced concrete
and masonry construction, discontinuities are frequently found in the envelope insulation and
air barrier systems. The overall heat loss from a building is due to transmission, ventilation and
infiltration through the envelope, assessed by measuring thermophysical properties (stationary
and dynamic), e.g. U-values for external walls, which in the last 20 years have been reduced by
two thirds, approximately from 0.9 W.m-2.K, to less than 0.3 W.m-2.K (Mazzoli et al. 2013). Indeed,
this issue must nowadays be correlated to new requirements for the adaptation to performance
standards and must be addressed within the domain of technique, through the contribution offered by scientific innovation.
The on-going research carried out by the DA - Department of Architecture of the University of
Bologna aims to investigate, optimize and promote new construction materials and technologies
to face the problem of energy retrofitting for existing building stock towards nZEBs, by an innovative solution, customised on different building typologies.

2. Objectives
In the domain of refurbishment interventions aimed to deeply renovate the existing buildings
up to nZEBs, one of the primary objectives concerns the energy efficiency of the façade solutions,
which are composed of surfaces that could be vertical, horizontal or