Dedicated outdoor air systems complement radiant floor to condition large volume enclosures. The air handling unit copes with ventilation loads and with the latent load of the zone to be conditioned. The floor handles partially or totally the sensible load of the zone. In these systems, the use of a solar desiccant air handling unit can be interesting. The paper proposes a combination of a solar desiccant air handling unit complemented with conventional cooling and heating coils. The objective is to analyse the interest of such an in a real building placed in two different climates in Spain, dry or humid. The control strategy has to be carefully studied because there are many possibilities to reach the required supply conditions to the zone. By means of a physical model implemented in TRNSYS, the interest of the proposed air handling unit is demonstrated in humid climates. Compared with conventional system, the solar desiccant alternative has 35% less of energy consumption. On the contrary, in dry climates the utility of the desiccant wheel is very limited and their use is not justified. (C) 2013 Elsevier B.V. All rights reserved.