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

detail of the façade of the private home of architect Henri Jacobs at Avenue Marechal Foch 9 in Schaerbeek, dating from 1899. An intriguing element can be made out beneath the window sills on the ground floor (fig. 16). It is a lovely sgraffito that “clothes” part of a technical installation: an air vent, decorated with the monogram of the architect, connected with the ventilation and heating system. This image reminds us that the introduction of technical elements into traditional Brussels houses is not a recent phenomenon. In his book, Les dimensions de l’ordinaire, Vincent Heymans presents the history of the traditional Brussels house from a heritage point of view as well as retracing the progressive introduction of technology. He shows the reluctance with which each of these technologies was greeted: running water; gas; central heating; electricity; bathrooms; etc. For example, in the 19th century, taking a bath was seen as dangerous and required certain precautions to be taken... Every one of these steps required modifications to buildings. The architect's role was, and remains today, to give architectural form to these new technologies which are not, in themselves, problematic.

NEW CHALLENGES FOR BUILDING TRADESMEN

The introduction of these new technologies meant that craftsmen were confronted with previously unseen issues. Roofers, for example, were faced with a complete transformation of the trade as a result of the changing requirements in terms of thermal insulation. In fact, the insulation in a roof is composed of different layers that it must be possible to manipulate and manage. Interior insulation of the existing roof space (i.e. between the rafters), which may be lined, does not pose too many problems for a roofer, as the technical details of the actual roof itself are not modified. However, in numerous cases - for instance where there insufficient under-roof height or existing finishes that need to be preserved -it is not possible to apply interior insulation. The solution proposed in this case is roof sarking, which consists of inserting the insulation on top of the rafters, requiring the roof to be raised. This technique involves redesigning all the details concerning water tightness and, in particular, the join between the roofing and the cornice gutter (fig. 17 to 19). Integration of thermal or photovoltaic solar panels, insulated cladding, etc.; all of these recent technologies are also a challenge for the trade.

As regards exterior joinery, extreme care is always required. Should it be replaced? Should the existing joinery be improved? Various techniques enable the performance of exterior joinery to be improved while preserving it. The fitting of a double frame on the inside is an efficient solution from a thermal and acoustic point of view. It is also possible to insulate a bow window by installing internal doors to create a buffer space. This blocks cold in winter and prevents overheating in summer. Thermally insulating the apron is also a possibility (fig. 20 and 21). However, all of this requires learning and acquiring new skills since a joiner

Fig. 20 and 21

Two examples of thermal insulation of bow windows: installation of internal doors fitted with low-emissivity glazing (left) and lining of the apron in order to install insulation (right) (photos by author).

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