The principal item of a full-scale lab preferably features a court-like facility where the 1:1 simulations are performed. Such lab facilities can be found at various architecture education centers throughout Europe. In the early eighties the European Full-scale Modeling Association (abrev. EFA, full-scale standing for 1:1 or simulation in full-scale) was founded acting as the patron of a conference every two years. In line with the conference title "Full-scale Modeling in the Age of Virtual Reality" the participants were particularly concerned with the relationship of physical 1:1 simulations and VR. The assumption that those creating architecture provide of a higher degree of affinity to physical than to virtual models and prototypes was subject of vivid discussions.

Furthermore, the participants devoted some time to issues such as the integration of model-like ideas and built reality thus uncovering any such synergy-effects. Thus some major considerations had to be given to the question of how the architectís model-like ideas and built reality would correspond, also dealing with user-suitability as such: what the building artist might be thrilled with might not turn out to be the residentsí and usersí everyday delight. Aspects of this nature were considered at the îArchitectural Psychology Meeting” together with specialists on environment and aesthetics. As individual space perception as well as its evaluation differ amongst various architects, and these being from various countries furnishing cultural differences, lively discussions were bound to arise.

In times characterized by the growing “architectural criticism” to the same extent as by the helplessness of the anonymous user the communication process between contractors, planer and users gains in importance. If communication is successful will not only depend on the quality of the project but also on the means of conveyance, e.g. visualizing or model representation. Can planning evaluation be effectively supported by virtual reality (VR)?

1. How do architects currently use CAD systems to produce drawings?

2. What are the effects of current CAD usage on product and performance?

3. What are the possible causes of current CAD usage?

4. What are the capabilities of the CAD medium and how can they be used efficiently?

The above four questions were addressed through the qualitative, quantitative, and cognitive analysis of data collected during an ethnographic study of architects working in their natural environment. The qualitative and quantitative analysis revealed that users missed many opportunities to use strategies that delegated iteration to the computer. The cognitive analysis revealed that missed opportunities to use such delegation strategies caused an increase in execution time, and an increase in errors many of which went undetected leading to the production of inaccurate drawings. These analyses pointed to plausible cognitive and contextual explanations for the inefficient use of CAD systems, and to a framework to identify and teach efficient CAD strategies. The above results were found to be neither unique to the CAD domain, nor to the office where the data were collected. The generality of these results motivated the identification of seven claims towards a general theory to explain and identify efficient strategies for a wide range of devices. This thesis contributes to the field of architecture by providing a detailed analysis of real-world CAD usage, and an approach to improve the performance of CAD users. The thesis also contributes to the field of human-computer interaction by demonstrating the generality of these results and by laying the framework for a general theory of efficient strategies which could be used to improve the performance of users of current and future computer applications.