In an analysis made to the civil construction sector and to its role in the national energy consumption, we argue the way this sector could contribute for the CO2 emissions at the same way it can contribute so that Portugal could fulfil the goals established by the Kyoto Protocol and stimulating other sectors of activity, witch have very restricted targets defined, to develop themselves. From the point of view of the sector of the construction in itself, the competitive advantages from the incorporation of sustainability principles are presented, especially in what it respects to the energy performance. The main conclusion of this paper is that the contribution of this sector can have advantages that we can define as having 4 dimensions: for the company in itself, for the consumer, for other sectors of activity and, consequently for the country development.