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

standards could not be met and installing double door systems to ensure the safety and evacuation of people. The questions posed were always extremely relevant. For example, Anne Lacaton wondered about the need to make a stairway fireproof given that the compartments already were, and as the stairways were split into two and stairs are clearly not to be used when a fire breaks out.

The conclusion from this second phase was that it was necessary to add one room per floor to maintain 97 apartments and satisfy the needs of the residents even in spite of the internal movements of tenants and optimisations. However, this work was never put into practice as, simultaneously, the Molenbeek Housing Company, understandably not very enamoured with the idea of an occupied renovation, decided not to rent out the apartments that were being vacated. The tower was therefore progressively emptied of its population, but the firm continued its work into finding ways to optimise the existing situation, believing that bringing the building into compliance did not make sense without this. As regards compliance with regional planning regulations, for example, following these to the letter would mean adding a small floor area to each room. However, this type of extension can only be carried out if the walls are destroyed, which is not in keeping with the spirit of the renovation, and only if the existing stairways are demolished and replaced by other, fire service compliant, versions.

Of course, Lacaton-Vassal's approach is all the more credible given that they have already worked on other towers in this way, most notably the Bois-le-Pretre tower in Paris which is almost the twin sister of the Brunfaut tower. In 2000, the firm undertook the renovation of this building with the simple idea of increasing the thickness of the walls based on a bioclimatic winter garden concept. The principle involves removing the existing façade and replacing it with a double façade (a double skin) with a three metre space between the two sections. This new space has to be managed by each resident as a small winter garden. Inside, the work carried out was very understated and extremely low tech, with a partition being adjusted here and there. One element that should be mentioned is that no double flow technology was used. The existing radiators were retained but the boiler was replaced. These minor renovations enabled energy performance of 78 kWh/m2/year to be achieved. This figure is far removed from the low energy standard required for the Brunfaut tower, i.e. 60 kWh/ mVyear, but hasn't this gap been largely offset by the savings made in terms of special technologies (including the embodied energy used to manufacture, transport, maintain and replace this technology)?

This study raises, in a somewhat obvious manner, the question of taking embodied energy into account when evaluating the sustainable nature of a project. Today, all possible on-board technical means are used: since 2007, only passive buildings with rainwater harvesting systems for bathrooms (systems which initially posed severe problems when they were combined with green roofs), thermal solar panels, photovoltaic solar panels, double flow systems, etc. are built in Molenbeek-Saint-Jean.

Fig. 13

The four pillars of sustainable development.



90 | The Brunfaut tower. Presentation of the conceptual design challenges of a renovation