Integrated BPE : a proposal to balance conservation and transformation in the sustainable reuse/rehabilitation project of existent buildings

ABSTRACT The Agenda 21 on sustainable construction states that maintenance, rehabilitation, re‐use of existing buildings are a fundamental strategy for sustainability. Since the 1970’s, part of the Italian architectural culture has been fighting a long battle in this direction, against the current “building wastefulness”. Italy owns an architectural heritage and natural landscape characters that deserve protection while needing rehabilitation and maintenance. Thus, research activities have been developing theoretical framework and design tools aimed at balancing the conservation issues and the transformation needs. The goals of preserving and protecting the architectural heritage and of upgrading the old building stock to environmental requirements, seem often to collide; they become less conflicting if we recognise that most historical buildings are not so badly off: most traditional buildings (before WW2) in Europe were durable (i.e. built to last for a long time) and, without efficient heating and cooling systems, assigned the users’ comfort to the envelope characteristics (thick walls, windows allowing direct control of natural ventilation and daylight etc.) This adds up to the more obvious considerations that old buildings stand on already serviced land and embody an enormous amount of energy and matter; it pinpoints the fact that environmental building rehabilitation must reduce to the minimum any removal (waste) of built matter. Thus, we need an approach where all the technical characteristic of the old building, as existing performances, are taken into account and do not get wasted in the rehabilitation process but feed the information/analysis design phase. This approach advocates a mutual adaptation of old buildings and new uses rather than a radical transformation of the old fabric aimed starkly at new performance levels; it also entails the consideration of the needs of the buildings themselves as well as of the users’ ones. Moreover, this approach – trying to make the most of what we already have ‐ allows to take into better account the other systemic values embedded in any existing built environment (economic, cultural and social ones). This paper presents the theoretical background achievements and the development of a design method, aimed at preserving the building identity and improving use‐adequacy and environmental sustainability. The case‐study shows the sustainable rehabilitation design process of an educational building in Milan, from the selection of relevant information for decision‐making at different design phases, to the different solutions according to different “priority values”. The method takes into account well established BSA methods at international level.