upon. An element is replaced only as a Last resort and when absolutely necessary. Reconstruction of an identical model is the exception rather than the rule. This approach is highly sustainable in and of itself.

I will summarise, based on this intervention philosophy and starting from the essence of the heritage conservationist's role, why in reality the heritage sector almost always locks horns with the energy sector, despite the energy performance exemption regulation applicable to listed monuments. This regulation is clearly necessary, but simultaneously illustrates the unresolved discrepancies. Furthermore, whether or not a project has permission to deviate from the standard, the applicant's starting point justly remains the improvement of the situation and/ or an increase in comfort.

The requirements of the Energy Performance of Buildings (EPB) energy performance legislation for building and renovating only apply when works are being carried out and a building permit is also required. However, in reality the opposite happens: an application for a building permit tends to be submitted in order to be able to carry out works with the intention of meeting the EPB standard.

The following section details the entire envelope of the building, the skin which forms the transition between a listed and unlisted environment, and the intervention plan for improving energy performance.

INSULATION OF THE FAÇADE

Historical façades come in many forms: these might be brickwork façades, austere or polychrome, with decorative masonry, interspersed with limestone or façades made solely of limestone, with sculptural elements or a rather plain Neoclassical façade in white lime plaster with simple mouldings (fig. 1 and 2). These examples are very typical of the Brussels development. None of these can be insulated on the exterior without losing their heritage value. Exterior insulation may be possible on very simple façades, though a great deal of detailed work remains with such an intervention. What about cohesion with the existing windows? These will be partially covered due to the thickness of the insulation, will appear to be embedded deeper into the façade than they originally were, and the sills will need to be adapted in order to disperse water. What about the eaves and cohesion with receding and protruding features? This type of intervention often leads to visually awkward or technically half-hearted solutions. The ultimate solution for a new-build project often proves to be a cumbersome operation and never-ending story for a renovation - if I renovate the façade, then I should also do the windows, the roof, the gutters, the extension, the neighbour, etc.

If exterior insulation is not possible, then we must use interior

Fig. land 2

Typical Brussels buildings. Left: Brussels residences around the turn of the last century (Ch. Bastin & J. Evrard © GOB); right: Neoclassical façade facing the Pachecogodshuis, Fermerijstraat, arch. H. Partoes, ca. 1830 (© GOB). None of these buildings can be insulated on the exterior without impacting their heritage value.

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