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THE ENERGY FUTURE OF EXISTING BUILDINGS IN BRUSSELS: BETWEEN PRESERVATION AND PERFORMANCE
time interval for each of the possible situations. Figure 7 shows the evolution of the temperature in the front façade. The simulation was always performed over a reference period of several years in order to obtain a balance of the moisture content in the wall. The graphs show only the evolution of the temperature and the moisture content during the last year of this reference period. A total reference period of three years was sufficient for the façade brickwork at the rear (the brickwork masonry only). A reference period of five years was needed to reach a balance for the brickwork on the front façade, with the ashlar in Euville limestone.
The evolution of the moisture content in the façade brickwork shows considerable differences between the front and rear façade, and also between the initial condition and both interior insulation options. Periods of heavy rainfall, mainly in the spring and autumn, can be easily recognised in the division of moisture content in the brickwork. The water is absorbed by the façade via the exterior surface, which is always shown at the bottom of the graphs. This evolution is easy to recognise via the change of colour, from red (dry, 1-2 vol. % moisture content) to green (wet, -> 10 vol. % moisture content). Subsequent drying of the brickwork follows the same pattern, but in the other direction. The analysis shows that the façade is saturated
| Material characteristic | Euville | Brick | Bricklaying mortar | Euville grout | Brick grout |
| Porosity (vol%) | 11 | 31 | 24 | 22 | 28 |
| Average pore diameter (µm) | 6.1 | 0.56 | 0.069 | 0.67 | 0.60 |
| Density (kg/m3) | 2310 | 1624 | 1789 | 1886 | 1676 |
| Water absorption coefficient (kg/m2s0.5) | 0.03 | 0.16 | 0.03 | 0.08 | 0.11 |
| Degree of capillary saturation (kg/m3) | 91 | 219 | 103 | 242 | 248 |
| Thermal conductivity (W/mK) | 0.7 | 0.6 | 0.7 | 0.7 | 0.7 |
| Moisture permeability (-) | 56 | 20 | 15 | 5 | 10 |
Table 2
Overzicht van de experimenteel bepaalde materiaaleigenschappen (© KIK-IRPA).
Table 3
Overview of the different calculation models for analysing the temperature division and moisture balance in the façade brickwork based on the interior insulation. The exterior wall of the façade is always on the left of the façade cross-section in the diagram (© KIK-IRPA).
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