The invention relates to epoxy resins cross-linkable at room temperature, including the product of a reaction of a mixture including at least one epoxy function carrier derivative, chosen from the group consisting of the non-polymeric, non-biosourced reagents and carriers of at least 3 epoxy end functions and the biosourced, epoxidized lipidic derivatives, and at least one crosslinking agent, the ratio between the number of epoxy functions being kept constant independently of the composition of the mixture, the method for manufacturing same, and the use thereof in composite parts for the mechanical engineering or for building construction and in structural parts.