A graphical tool to predict the daylight availability within a room at the earliest design stages

This paper presents a graphical tool which is intended to be used during the earliest design stages to predict the daylight amount within a space as a function of different architectural features. The daylight amount is expressed in terms of Daylighting Dynamic Performance Metrics, DDPM, resulting from a climate based daylighting simulation. The tool was built based on the results from a parametric study carried out for a sample room with different room orientation and depth, window area, visible transmittance and external obstruction angle. The analysis was repeated for three sites, representative of different climate conditions (Turin and Catania - Italy - and Berlin – Germany). The paper describes the graphical tool which was developed and how it could be fruitfully used by the design team to predict the daylight availability within a space. Potentials and drawbacks of the proposed tool are also discussed in comparison with other tools which are commonly used during the earliest design stages of the daylighting design process (such as the average daylight factor formula or the recent software Lightsolve). It is shown that the information obtained through the different tools is consistent and that the proposed graphical tool can be useful for the design team, as it offers different information about the daylight availability within the designed space.