THE ENERGY FUTURE OF EXISTING BUILDINGS IN BRUSSELS: BETWEEN PRESERVATION AND PERFORMANCE

Load on the original structure and to apply good, complete insulation. Because these leave the physical space within the original structure of the roof untouched, the extra height becomes even more noticeable (easily 15 cm).

Interior insulation is also an option, though of course not if the roofs interior surface has an aesthetic finish as shown in the example in figure 14.

Skylights made of classical T, L and I moulding which form complex, refined structures cannot (in most cases) bear the weight of insulated double-glazing or safety glass (fig. 15 and 16). In many cases they are rebuilt with sturdy, modern mouldings.

The extra load of the added insulation often causes structural problems, thus making the original roofing beams structurally unsuitable. They must therefore be supported or replaced, sometimes with the replacement of the entire roof as a consequence.

HERITAGE CONSERVATION VERSUS ENERGY PERFORMANCE

The contradiction between heritage preservation and energy performance manifests as a conflict between two sides: restoration-intervention.

For instance, a thorough investigation of the monuments’ building elements might be conducted, but the evaluation of their value is threatened by performance requirements which are inflexible and have top priority. There is consequently no more room for the study.

Not only is research into the value of the existing elements lacking, but the evaluation of the effects and side-effects of the mandatory improvements are seldom really thoroughly examined. Nor is the actual performance of old buildings carefully examined; real knowledge of the buildings and all their characteristics has not yet been acquired. The limited research we do have already shows, for example, that the values for actual energy consumption deviate greatly and are mostly much lower than the theoretical values. We seldom see evaluations for the prioritised improvements to be carried out or a thorough investigation to determine what the most gainful intervention actually is. The intervention occurs before knowledge has been acquired and research carried out.

In a second example, the measures proposed or taken might be in complete contrast to the sustainable intervention hierarchy.

These examples clearly illustrate that in the approach to improve the energy consumption of the elements in existing buildings, replacement and reconstruction often take precedence and have become more the rule than the exception. This is not at all the objective of heritage preservation and actually completely misses the point.

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