The system performance was evaluated in terms of provided comfort and energy efficiency. Then two indicators were introduced and calculated by dynamic simulations.

At every simulation time ti the predicted mean vote in the test room was calculated. According to the recommendations of the international standard ISO 7730 the PMV should lie in a comfort zone defined by the condition: -0.5 < PMV < 0.5 [13]. Then a discomfort index was defined as:

N

discomfort = ^ D(ti)

i=1

_(PMV(ti )At if PMV(tt) > 0.5

Dt‘) [0 if PMV(ts) < 0.5

where N is the number of time steps in the simulation period and At is the time step. The discomfort was calculated for the test room 1 in free floating and for the same room cooled by the system, using the same time step of 1 hour. Then a relative discomfort index, comparing the two conditions, was defined as:

where Qroom is total heat removed from the test room by the system in the simulation period and Epumps is the total electricity consumption of the pumps in the same period.