Energy optimisation of lightweight 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 leads to changes in 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 in buildings with lightweight facades – as well as being problematic from a dampness point of view – can lead to considerable inconvenience for residents/users both during the process and afterwards, in terms of altered floor area and different wall materials, etc. Exterior insulation is easier to fit, reduces heat loss and renews the lifespan of the facade, but at the same time it represents a major intrusion into the building’s architecture and can often change the appearance completely. Retrofitted exterior insulation should be finished off with a new protective cladding of e.g. either sheeting material or brickwork, depending on the preferences for the building’s outward expression following the energy optimisation.

Photos: Enemærke & Petersen A/S