In this thesis we study the possibility to introduce the concept of style in declarative modelling in order to aid architectural design during the conceptual phase. In order to study such a hypothesis we have develop a methodology of architectural conceptual design utilising style. The method is based in the frame of declarative modelling, and evolutionary algorithms. In particular, we develop a framework for the modelling of architectural knowledge. We define a model of style based on the declarative conceptual cycle. Moreover we develop a new engine for the generation of solutions. This engine is based on multiobjective genetic algorithms. The result is a system prototype for Evolutionary Declarative Design-MultiCAD for the aid of conceptual architectural design. The resulted method could successfully quantify aesthetic qualitative criteria of a building. Our system points towards a computer aided aesthetic design tool.