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

example, is particularly sustainable. Thanks to its assembly, historical woodwork also allows for easy local repairs. Consequently these elements can attain a considerable life span (fig. 6 and 7).

Some of this historical woodwork can be perfectly equipped with double glazing, subject to adaptation of the groove to accommodate the thicker, double-glass sheet. In most cases however, the necessary fitting of a thicker glass sheet means that the woodwork must also be replaced. Not only can a groove often not be made large enough, but the original woodwork is often not strong enough to carry the extra weight of the glass sheets. Furthermore, extra air-tightness is also often a requirement.

In this circumstance the choice is often made to use a remake of a quasi-identical model. Depending on the quality of the original woodwork, this may or may not be tolerated. Even if the remake is a solution for woodwork of low value, it is not a solution from a heritage point of view if the original woodwork is still in good condition or has a design of exceptional quality.

Another aspect is the quality of the glazing itself, because even if the window frame is strong enough for an insulating glass sheet, decorative glazing and examples of remnants of glass production from the past (such as pulled and blown glass, crystal, etc.) still require a different approach (fig. 8 and 9).

In many cases, a double window or secondary glazing can be a good and technically feasible solution, yet this is only used sporadically (fig. 10). Even when replacing a window by a higher performance one, this too can become an ongoing saga.

Fig. 6 and 7

Restoration of doors, Vanderschrickstraat, 1060 Brussels (© GOB).

Fig. 8 and 9

The quality of the glass also influences the choice of intervention. Decorative glazing and remnants of glass production from the past, such as pulled and blown glass or crystal, require a different approach (© GOB).

Fig. 10

In many cases, double glazing or secondary glazing can be an effective and technically feasible solution. It has been used as a solution for a long time now. Knuyt de Vosmaer House, Rue du Congrès/Congresstraat in Brussels (© GOB).

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