ONLINE BRUSSELS HERITAGE - ONE-DAY SEMINAR - 11/12/2014

that can be used to determine the extent of work possible. We have compared sectors and sequences of buildings. A perusal of the archives and planning permission records has enabled several facts to be identified concerning these sequences. I am going to focus on three such sequences.

The first is located in Ixelles, in the Berkendael quarter (fig. 5). Ordered and symmetrical, it concerns a housing development. The developer presumably used a catalogue from which his customers selected what they wanted. He arranged it so that two similar buildings would not appear side by side and designed his sequence. He played around somewhat with the symmetry, striving for consistency, in the end creating an urban street-scape. However, an exception can always be seen at each end, where the buildings stand out in some way so as to constitute urban landmarks. Here, if we take one of the buildings and insulate it externally, the streetscape will suffer. In this case, the heritage issue is not at the building scale but at street scale.

Our second example of a sequence is situated on Rue Eeckelaers, in Saint-Josse-ten-Noode (fig. 6). Composed of mixed stock, it is most likely the result of successive modifications. It is difficult to give an opinion without seeing the buildings up close. However, it can be said that insulating one of these buildings would not fundamentally alter the appearance of the street. These are typical examples from the 19th century and are undoubtedly the subject of less attention from a heritage point of view.

The third sequence concerns housing types from the 1950s, which, in my opinion, offer some fairly interesting elements. Their construction is still quite traditional while also incorporating pre-fabricated components, such as the window frames. In Woluwe-Saint-Pierre, these types of houses offer a coherent sequence with regard to the Town Hall, which is part of a vista. While the buildings, taken separately, do not arouse much sympathy from a heritage point of view, there is nevertheless a coherent sequence. Modifying any one of these buildings would affect this coherence even though the Town Hall is behind them. In fact, its construction marks the completion of the quarter and the streetscape sequence in which it is perfectly integrated. Conversely, the sequence on Rue Francois Gay, composed of older housing types that feature heritage elements, is mixed. Modification of an individual building would not pose any particular problem here (fig. 7).

Urban form therefore enables heritage to be viewed from the perspective of sequences without focusing on the building and its details. Working at this scale also involves examining the relationship between the buildings and their immediate environment, and considering their sustainability, their vulnerability, and their ability to cope with climate change.

The increase in energy prices and the population explosion will tend to bolster the process of densification of the existing city, particularly for the inner ring with its consistent land use availability. To what extent, therefore, are the public authorities likely to act? To what extent must densification be managed? Urban planning must facilitate this phenomenon while at the same time protecting the intrinsic qualities of existing fabrics, which means giving special attention to existing green spaces (conservation, removal of barriers, enhancement, etc.), anticipating the emergence of urban heat islands, identifying the landscape qualities of architectural and urban compositions, etc.

THE IMPLEMENTATION OF ENERGY EFFICIENCY MEASURES IN OLD BUILDINGS

The selection offers a range of housing types covering a period of one hundred years, from the first half of the 19th century up to the post-war period. It involves ordinary architecture, the most common stock type, as well as a garden city. Here, I will address some of the types, the use of materials and their thermal conductivity.

We were surprised by the systematic use of brick and its persistence over time along with the late presence of wooden floors, which certainly raise questions during renovations. As regards the thermal conductivity of the walls, the target -perhaps not overly ambitious-was set at 0.4 (the bar is currently 0.2). In general, the buildings studied are not insulated and place us within a classical analysis scheme.

The evolution of buildings

The first change to be noted is the materials used. Throughout the 19th century, construction methods remained traditional but the range of materials, which were increasingly mass-produced, expanded and enabled the style of architecture to become more diversified. In this respect, the difference between Neoclassicism (where the bricks are rendered) and Eclecticism (where the materials are exposed) is striking (see pp. 17). The limited use of dense, and therefore conductive, materials in eclectic architecture resulted in a decline in the energy efficiency of buildings (fig. 8)

28 | Urban forms, typology and improving the energy efficiency of old Brussels buildings