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Calculations of masonry heat conductivity and resistance were carried out as per EN 1745: 2002, EN ISO 6946: 1996 and EN 8990, and on the basis of measurements obtained from EN 12664: 2004. All tests were carried out at the CSTC. |
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| Type |
Vertical joints |
Heat conductivity (W/mK) |
Transfer coefficient U(W/m2K)* |
Heat resistance R (m2K/W)** |
| 14 cm Blocks |
| Block |
NA |
0,247 |
NA |
NA |
| Wall |
Open |
0,251 |
1,38 |
0,56 |
| Wall |
Closed |
0,251 |
1,38 |
0,56 |
| 19 cm Blocks |
| Block |
Open |
0,285 |
NA |
NA |
| Wall |
Open |
0,289 |
1,21 |
0,66 |
| 29 cm Blocks |
| Block |
Open |
0,266 |
NA |
NA |
| Wall |
Open |
0,270 |
0,8 |
1,07 |
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* : Rsi and Rse included
** : Rsi and Rse not included
NA : Unavailable (no measurement for this characteristic)
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Research carried out by the Architecture and climate research centre of UCL shows that thermal effusivity is similar to the sensation of touching the walls (a warm sensation if effusivity is low, and cold otherwise). BESTO® blocks have very low effusivity (see Figure 1). The thermal behaviour of a BESTO® wall is roughly halfway between that of wood and that of terracotta blocks.
Figure 2 illustrates the fact that the temperature of the wall surface Twall is as important as the air temperature Tair on the feeling of comfort felt by a resident. It is worth remembering that the level of comfort in a residence is defined by the formula Trs = (Twall Tair) |
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| Figure 1 |
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| Figure 2 |
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