In the early phases of the building design process, decisions are made on certain geometrical parameters, which strongly dictate the future performance of the building. To support decision- making, an understanding of the relation between design parameters and performance is essential. This paper presents the results of two parametric studies conducted to investigate the impact of specific design parameters on three performance indicators related to solar potential and thermal and visual comfort. Results indicate which parameter has the strongest impact on each indicator and provide useful and potentially non-intuitive insights into the dynamics of building performance.