Radiant cooling and dehumidification system coupling: comfort and energy analysis for residential buildings

The development of radiant cooling has stimulated the interest towards new system solutions based on coupling the ventilation strategy with radiant cooling. Radiant cooling system may cause condensation on the active surface under hot and humid conditions during the cooling season. This phenomenon occurs when surface temperature falls below dew point. To avoid condensation it is important to reduce air humidity with dehumidification device or mechanical ventilation system. In this regard, the possibilities are essentially two: on the one hand there are dehumidification devices that reduce humidity with no coupling to ventilation, i.e. the air inside the room is dehumidified and ventilation is left to simple system of infiltration; on the other hand mechanical ventilation system may have dehumidifying finned coils. In order to analyze the building-plant system of a typical residential dwelling in a multi-storey building, the simulation tool DIGITHON Multizone (developed by the University of Padova) has been used. This model is based on the resolution of the equations of balance in the room, by means of the transfer functions for solving the problem of unsteady state thermal conductivity through walls. Six different solutions in different climatic conditions have been analyzed: radiant cooling without dehumidification, radiant cooling with a soft dehumidification device, radiant cooling with a dehumidification device which supplies sensible cooling as well, radiant cooling with a mechanical ventilation system which provides dry and cool air and radiant cooling coupled with fan coil. The aim of this work is to compare different HVAC coupling solutions, in terms of indoor environmental comfort and energy savings, highlighting the importance of air handling with radiant cooling systems.