| Keywords |
Opaque exterior wall ; Thermal transmittance ; Thermal resistance ; Average method ; Convergence |
| Abstract |
This study analyze the convergence of the in-situ thermal transmittance calculated by average method following ISO 9869-1 to the increase and change of measurement period. The measurement was conducted for an opaque exterior wall of an apartment house over a period of two weeks during winter. As a results of the measurement, the termination conditions were satisfied after eight days, more than twice the minimum required measurement period of three days, even though the experimental conditions recommended in ISO 9869-1 were met. The findings show that as the measurement duration(DT) increased, the termination condition that the thermal resistance obtained at the end of the test must not deviate by more than ±5% from the value obtained 24 h earlier, were easily achieved. On the other hand, other termination condition that the thermal resistance obtained by analyzing data from the first time period during INT(2×DT/3) days must not deviate more than ±5% from the value obtained from the data for the last period of the same duration are relatively difficult to achieve. This is because the environmental parameters of the first and last time periods must be similarly maintained within a stable range. |