Before implementing an engineering system in the design process are studied different proposals to evaluate and rank them. In this evaluation process several experts assess different aspects and criteria according to their knowledge and preference on them. These criteria may have different nature (quantitative, qualitative) and the experts could belong to different areas and have different knowledge on each criterium, so the assessments used to express the value on each criterium could be assessed with different types of information (numerical, linguistic, interval-valued). In such a case, to select the best proposal we must deal with this heterogeneous information to evaluate and rank the different proposals. In this contribution we show different fuzzy approaches for dealing with heterogeneous information.