The present research project establishes the basis of a decision making tool, based on an ontology, to integrally analyze Environmental and Health and Safety risks along the planning and execution phases of a construction project and to define technical solutions and preventive measures. The ontology will allow the classification of all the terms (aspects, impacts, risks, and procedures) related to the Health and Safety Evaluation and to the Environmental Evaluation as well as the relationships that exist among them. On the other hand, each class will be enriched with different properties that will be used by the decision-making tool to identify the main significant Environmental and Health and Safety aspects in each Construction process, and moreover, to evaluate their impact in a specific construction project in order to provide procedures. Therefore, both designers and contractors will asses the environmental and the health and safety risks related to each designed solution or constructive process, facilitating them the choice of the designed solution with fewer impact/risk. As a consequence the construction sector will increase its competitivity by optimizing the resources dedicated to the different management systems of a construction company.