The test building is located in the outskirts of Milano. At the first floor there are two test rooms having the same volume, the same exposure of the windowed facade and the same internal loads. The rooms are equipped with radiant panels formed of small pipes, installed into the ceiling in test room 1 and into the walls in test room 2. The pipes are made of polypropylene and have an external diameter of 3.35 mm and a thickness of 0.5 mm.

The experimental system layout is shown in Figure 1. It consists of two water loops: a rooms loop, containing the radiant panels and removing heat from the building, and a ground loop, containing the earth-to-water heat exchangers and discharging heat into the ground. Thermal interaction between the loops is achieved through a counter current flow heat exchanger. Each loop is provided with a pump.

The ground heat exchanger consists of 10 vertical steel pipes 6 m deep connected in parallel. The pipes are arranged in two parallel lines in a rectangular pattern. The distance between adjacent tubes is 1.5 m. Each element consists of two concentric tubes so that warm water coming from the building flows down through the hollow space between the outer and the inner tube and flows back into the inner tube. A layer of insulating material
covering the internal tube prevents heat transfer between the descending and the ascending fluid.

A monitoring system collects data with a time step of 10 minutes. The following quantities are measured:

— in the test rooms: air temperature, mean radiant temperature, radiant panels surface temperature, air humidity

— in the rooms loop: water temperatures at the inlet and the outlet of the radiant panels

— in the ground loop: water temperatures at the inlet and the outlet of the earth-to-water heat exchanger

— in the ground: temperatures at different depths (1.5, 3, 4.5 and 6 m) in the perturbed and in the unperturbed zones

— meteorological quantities, i. e. outdoor air temperature and humidity, wind speed, global horizontal solar radiation

The water mass flow rates are measured with variable area flow-meters by manual reading. Power consumption of the pumps is measured through electricity meters.