High-efficiency rehabilitation of (semi-)identical urban housing ensembles: Experience-based guidelines for Architectural Industrialized Multifunctional Envelope Systems
The evolution of industrial processes and modern computer-commanded machinery offers innovative techniques for the retrofitting of building envelopes: Architectural Industrialized Multifunctional Envelope Systems (AIM-ES). The old building is “wrapped” with a new envelope made of large prefabricated elements, mounted on top of the existing walls. By doing so, the on-site operations are shortened and occupants suffer from less nuisance and can keep usage of most of their living space. The technique also offers to extend the volume of the building, enabling interesting perspectives from an architectural point of view. Moreover, the integration of building services in the new envelope (e.g. HVAC ducts and systems, solar technologies, sun blinds) opens the way to a more holistic approach of retrofitting, with so-called ‘multifunctional’ façade elements. The ‘holistic’ feature is also to be found in a new in-depth interaction between actors, ensuring an improved quality in terms of environmental quality, energy efficiency, and indoor comfort. The study of this new approach was undertaken in the AIM-ES (2013-2014) and AIM-ES Performs! (2015) projects.
AIMES façade modules can be designed in many ways, the five key parameters being: (1) the structural approach, (2) the size and orientation, (3) the composition and level of prefabrication, (4) the characteristics of the interface between the new and the old envelope, and (5) the level of technicality. Generally, due to the cost implied by a heavier conception and investigation phases compared to traditional refurbishment methods, such industrialized envelope systems are more suited for the rehabilitation of large buildings or building complexes with a high degree of repetition. Overall, we can say that the AIM-ES method arises as a very interesting solution in a context of intensification of deep retrofits. Although it is not suitable for all types of projects, prefabrication coupled with integration of services is gaining popularity, because of the quality assurance / improvement and the reduction of on-site nuisance that are intrinsically linked to it.
During the last decades, tens of buildings were renovated throughout Europe with the AIMES method. In parallel, some pioneer research projects initiated the scientific contextualization of these innovative techniques. Much information related to prefabricated envelope systems for retrofitting is already available in literature, in the form of project reports, scientific papers or technical documentation. Several – mainly wood-based – module systems already proved a great potential (fast on-site execution, high quality construction, cost-effective, reliable, etc.) but are not widespread, nor well-known, certainly not in Belgium. Such innovative technique, however, could help to stimulate the renovation initiatives in Belgium. The reference document elaborated during the AIM-ES project wants to resolve this problem by providing guidelines addressing the actors of the retrofitting sector so that pilot projects can be encouraged in Belgium. In that context, the essential information is summarized, with a focus on critical design and decision parameters.