Energy optimisation of heavy facades

Type 5: 1960-2000

Initially, the extent of thermal insulation applied to industrialised multi-storey housing was quite limited. It was not until the 1970s, when the effects of two oil crises led to increased energy costs, that the building regulations were tightened in this regard and external walls with more insulation started to appear. However, with today’s standards on low energy consumption in buildings, a large number of these developments do not live up to current requirements on low U-values for exterior walls, and many projects have therefore been set in motion to retrofit insulation – either internally or externally.

Retrofitting insulation to finished buildings is not without its problems, from both a technical and an architectural point of view. The retrofitting of insulating materials results in changes to the temperature and moisture-transmission relationship in external walls, which, if not properly handled, can lead to problems with dampness and mould fungus. It is also unclear whether it is better to insulate on the inside or outside. It depends on the specific technical conditions and materials. Applying insulation internally to concrete buildings may be sensible enough in itself, but has a significant impact on the residents/users, both during the installation process and afterwards in terms of altered floor space and different wall materials, etc. Exterior insulation is easier to fit and also reduces heat loss, though at the same time it represents a major intrusion into the building’s architecture and can often change the appearance completely. The heavy concrete elements will easily support the extra insulating materials and, in most cases, some kind of finishing and protective cladding. However, special fixtures and solutions will often need to be designed and developed in order to join together the old and new structures.

Photo: Jesper Engelmark