||The paper discusses the early results of Virtual Project Environment [VPE] implementation that uses Product Data Technology (PDT) and Knowledge Technology (KT). The VPE is a computer environment that provides actors with the ability to simulate the project in the early design process. The system gives actors the opportunity to create and evaluate a number of alternative solutions. In the current implementation, the system is filled with project templates and knowledge about office buildings. Functional requirements, resources like i.e. available money, location and design solutions can be put as project data in the system. By applying knowledge rules, case rules and default values, the system will supplement this project information and generate a more detailed alternative. This means that KT is used to detail the requirements and solutions. This process assures the availability of just enough project and product information to conduct performance evaluations. These evaluations can be feasibility studies on relevant aspects like energy consumption, durability and costs. These studies give actors in this early phase a better view on the project. Working with such a system, actors can put in their design decisions and see what kind of result it has on the total project. For example the client as actor can change his demands. The VPE uses KT to adjust the design automatically. The actor can directly see what the consequences are of his change.The basis for the VPE is a product model. Modeling the early phases means among others, that the product model must capture many different levels of detail. For Example when a client wants to have new office accommodation, initial requirements can be the amount of people it has to house. KT can be used to estimate the total size of the accommodation. Having an initial idea of the shape estimation can be made of the size. In a later project phase the needed space is requirement more explicitly. The design is at that phase also more detailed. In the early design, a building must be modeled using non-detailed information. In the early design, these rough descriptions are worked out to more detailed descriptions. The product model, supporting this process, must also support the detailing process.This means different levels of detail must be supported for every product model object. For example, in the beginning of the process, a building will be described using only a primitive shape (box, cylinder, etc) and some initial properties (amount of storeys, main function, etc). Later in the process the building will be modeled with more detail. The shape is refined, the interior of the building is more detailed, etc (see figure 1). The paper discusses how this project data can be captured with PDT. Furthermore the paper discusses how this product model can interact with knowledge.