In situ measurement of thermal transmittance and thermal resistance of hollow reinforced precast concrete walls

• Thermal performance of precast concrete walls was evaluated by in situ measurement.
• Thermal transmittance depends on wall orientation and outside weather conditions.
• Thermal resistance is independent of the wall orientation.
• In situ mean thermal transmittance lies in the range of 1.459–1.803 W/m2 K.
• Six days is sufficient to ascertain the in situ thermal performance parameters.

A study was conducted to determine the in situ thermal transmittance and thermal resistance of two exterior reinforced precast concrete walls of a building constructed with hollow panels. The results indicate that the North and East facing walls have a mean thermal transmittance (air to air) of 1.459 and 1.803 W/m2 K, respectively. The mean thermal resistance value (surface to surface) of the North and East walls is 0.355 and 0.352 m2 K/W, respectively. While the thermal transmittance depends on the wall orientation and the outside weather conditions, the thermal resistance is independent of the wall orientation. The results also indicate that a monitoring period of six days is sufficient to ascertain the in situ thermal transmittance and thermal resistance of reinforced precast concrete walls.