It is necessary to design carefully each detail to realize low-energy-consumption buildings; the overall achievable energy saving will be represented by the sum of the ones obtained from a good realization of each component: facades, roofs, glazed surfaces, etc. In this paper the convenience of using ventilated roofs for the reduction in summer thermal loads is investigated. Particular attention is paid to the case of roofs with small-sized-thickness duct in which the air flow is laminar (microventilation). The obtained results show that an energy saving, even exceeding the 30%, can be achieved by using ventilated roofs in summer, compared to the same non-ventilated structure. (c) 2004 Published by Elsevier Ltd.