A ventilated cooling ceiling with integrated latent heat storage—Monitoring results

• Ventilated cooling ceiling with PCM was monitored in two offices and a conference room.
• The cooling ceiling with PCM reduced operative room temperature by up to 2 °C.
• The cooling power of the airflow was relative small, a big part of the total cooling power of the system was by heat transfer through the ceiling.
• About 5 kg/m2 of PCM was sufficient.
• For an efficient regeneration of the PCM, the cool outer air should reach the PCM directly.

A ventilated cooling ceiling with integrated phase change material (PCM) as latent heat storage was installed in two offices and a conference room. The ceiling was rear ventilated to improve the heat transfer between PCM and room air and its cooling properties were monitored during summer 2009 and 2010. During the day, the ventilation was purely in circulating operation, while cool outside air was used during the night to regenerate the PCM. The ventilated ceiling with PCM reduced the maximum operative room temperature in the office rooms by up to 2 K compared to a reference room without cooling system. For an operative room temperature of 28 °C and a volume flow rate of 300 m3/h, a cooling power of 30 W/m2 was measured in the conference room. In the demonstration rooms, it was not possible to insert the fresh air directly onto the PCM as planned. Instead, the outer air entered the rooms via tilted windows or ventilation flaps in the façade, so the cool night air did not reach the suspended ceiling but instead sank to the floor and mixed with the warmer room air. Due to this, the PCM in the suspended ceiling often could not be regenerated completely.