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

When a building is sub-divided, the issue is more complicated than in the case of a single-family dwelling. In effect, each apartment is generally equipped with a separate ventilation system. This system takes up room as all the pipes have to be placed somewhere. The solution devised for the project illustrated in figure 11 was to fit a very large moulding, pierced by small circular openings, in front of one of the ventilation ducts in order to integrate it visually into the ceiling moulding.

We'll now focus on the renovation of a private home in Schaerbeek (fig. 12). It is a neoclassical building, of which there are thousands in Brussels. This project is especially interesting in that it succeeded in reconciling an ambitious approach to energy efficiency with a concern for preserving the heritage value of the building, even though compromises had to be made (such as replacing all of the window frames). The low energy standard (under 60 kWh/m²/year), was easily achieved. By way of comparison, the usual consumption of a building of this type is somewhere around 150 kWh/m²/year. The energy accounting religiously maintained by the owners indicated, for the first year of occupation, energy use of 42 kWh/m²/year for heating, which is quite close to the consumption calculated when the project was being developed: 32 kWh/m²/year. The rear façade was of no particular architectural interest. It was therefore insulated externally and covered with new render. The blue stone window sills, which acted as thermal bridges, were replaced by aluminium sills. Similar work could not be envisaged for the street-side façade for heritage and urban planning reasons. Interior insulation was therefore chosen, even though this technique is more difficult to implement as it often has the result of enhancing the thermal bridges (fig. 13). Contrary to usual practice only the lower part of the walls was insulated, which avoided having to encroach upon the ceiling mouldings with the overlapping insulation. Although only partial, this interior insulation provides significant comfort as it eliminates radiation of cold from the wall surfaces closest to the body. What's more, there are a sufficient number of non-insulated surfaces remaining, avoiding the concentration of any dampness in a specific point on the wall. The risk of spot condensation at the point where the floors are anchored into the façade is therefore reduced. Another interesting aspect of the project is the housing of the ducts for the double-flow ventilation in the old chimney flues (fig. 14). This operation ties in with the original function of chimneys which also played a role in building ventilation. They were

Fig. 10 and 11

Close-up of interior wall insulation where it meets the ceiling (left); perforated moulding concealing a ventilation duct (right) (photos by author).

110 | Sustainable renovation of a Brussels house: a challenge for building tradesmen