Abstract
As the European building stock is in evident need of deep energy retrofitting to meet current European
decarbonisation targets, the construction market calls for industrialised systems to boost massive
renovations and activate economies of scale. The article outlines the development of an offsite fabricated
system for building energy refurbishment through rainscreen façade elements. A focus is placed on
such elements as they offer excellent system integration possibilities and the opportunity to boost the
level of offsite fabrication, compared to other already industrialised façade systems, such as unitised
façades. This research was carried out within the framework of BuildHEAT research project, funded by
the European Union Horizon 2020 framework programme. The system concept is based on a systemic
approach that combines energy efficiency, multifunctionality, integration of renewable energies, and
ease of installation as design drivers. System development has rolled out through different phases, with
an increased level of detail. During the schematic design phase, a set of different prefabricated façade
panel dimensions were analysed. Afterwards, the component and system integration were assessed
according to their impacts in terms of energy performance and fulfilment of mandatory technical
requirements. As a last step, the most promising technical combinations underwent detailed design to
verify construction feasibility and eliminate any bottlenecks during the fabrication phase. Results show
that the proposed prefabricated solutions allowed: (i) simplified active system integration (photovoltaics,
solar thermal, and building services), (ii) ease of installation on site, minimising the impact of renovation
actions on occupants without compromising on final quality and reducing installation costs. Current
limitations to extensive market diffusion of the system are related to two main aspects: (i) the need for
on-site adjustments; and (ii) increased manufacturing costs compared to traditional external insulation
interventions (e.g. ETICS). The current cost of the system (2020) is in the range of 3 - 1.5x the cost of,
respectively, an ETICS or a vented rainscreen façade. However, as a next step, including the life-cycle
perspective in the calculation, as well as accounting for economies of scale, the system will be evaluated,
expecting a cost figure comparable to the rainscreen façade