The outer wall of the residential building was built of ceramic blocks, thickness 36 Cm, whose volumetric density is 1800 kg/m3. From the inside, a layer of plaster made of lime and gypsum mortar of thickness was applied to the wall 1,5 Cm. External plaster thickness 2 cm is made of cement-lime mortar. Please calculate the value of the k-factor for this external wall and determine the thermal insulation. Necessary data for calculations:
Thermal conductivity coefficient for ceramic hole blocks, volumetric density 1800 kg/m³ : 0,81 W/(Mk)
Thermal conductivity coefficient of lime-gypsum mortar: 0,70 W/(Mk)
Thermal conductivity coefficient of cement-lime mortar: 0,87 W/(Mk)
Heat inflow coefficient: 0,13 m²K/W
Heat outflow coefficient: 0,04 m²K/W
Calculation of the value of the thermal conductivity coefficient:
| Arrangement of layers in the partition (from inside to outside) | Layer thickness in m | Thermal conductivity coefficient in W/(Mk) | Thermal resistance in m²K/W |
| Internal lime and gypsum plaster | 0,015 | 0,70 | 0,02 |
| Wall made of ceramic hole blocks,
volumetric density 1800 kg/m³ |
0,360 | 0,81 | 0,44 |
| Cement-lime mortar plaster | 0,030 | 0,87 | 0,03 |
| = total heat flow resistance | 0,49 | ||
| + – heat inflow coefficient (constant value) | 0,13 | ||
| + – heat outflow coefficient (constant value) | 0,04 | ||
| Total thermal resistance 1/k | 0,66 | ||
| k (heat transfer coefficient) | 1,51 W/(m²K) | ||
Method of calculation: heat flow resistance equals the thickness of the material layer, in m, divided by the thermal conductivity coefficient.
Thermal insulation of the analyzed partition does not meet the minimum requirements for buildings subject to thermal protection. Additional insulation of external walls is necessary.