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During the last years much interest has been paid to Low Temperature Systems, i.e. systems which use water to transfer the energy and have temperatures of this heating-cooling medium close to room temperature (20 °C for cooling, 26 °C for heating). Such systems show an overall energy consumption lower than for conventional air-conditioning systems and offer the possibility of using renewable or recovery sources of energy, or technologies not usable in traditional systems, such as condensation boilers, reversible heat pumps, evaporation exchangers, ground heat exchangers or water beds. With these equipments higher COP than in traditional systems can be obtained.
To allow a correct design of a radiant system and the correct coupling with energy sources it is necessary to have a tool and a guideline available to evaluate, in his complexity, the physical system building-plant-environment. The high number of parameters describing such a system, as well as the problems related to conduction heat transfer in unsteady state conditions, need the use of dedicated numerical models.
In this work the design of a pilot building located in Padova (Italy) is presented. This building is equipped with a novel type of thermal active slab feeded by a reversible heat pump coupled to ground heat exchanger. The design is based on the concept of night time heat-cool storage and variable comfort conditions during daytime. The simulation results show a strongly reduced maximum heating-cooling capacity (peak-shaving) and a better energy performance in comparison with traditional HVAC systems. The simulations have been carried out by means of TRNSYS as for the building and by means of a model called CARM as for the ground field.