A one week measurement campaign was carried out in August 2003. The test room 1 was cooled by the radiant ceiling connected to the ground heat exchanger, while the test room 2 was left in free floating and used as a reference. The system operated uninterruptedly 24 hours a day with a mass flow rate of 520 kg/h in the ground loop and of 360 kg/h in the rooms loop.

The time evolution of the operative temperatures in the cooled and in the free-floating reference room are reported in Figure 2 together with the surface temperature of the radiant ceiling and the outdoor air temperature. The data show that the system was able to lower the operative temperature of 4-5°C with respect to the free floating situation. The total power demand of the two pumps was 91 W and the average thermal power extracted from the test room was 454 W. The coefficient of performance (COP), defined as the ratio between the removed thermal power and the electricity demand, is then equal to 5.