In order for a virtual environment to be effective as a designing platform for digital architecture, it is not enough to focus on the precision of the renderings and the accuracy of simulated behaviours. The environment should provide appropriate design support to its users. Design objects are rarely isolated; they are always in the company of other objects. Design spaces are constructed from the relationships between these objects. This paper presents a framework of developing virtual environments in which design semantics (high level relationships between objects) are incorporated into intelligent agents. These agents monitor designers' actions and provide design guidance and assistance. The agents interact with objects in the environment and with designers. This paper describes the features of the proposed framework, design semantics and activities that agents are expected to support.