The rise of technological advancements has come at a time of heightened awareness of the importance of analysing our cities' environmental impact, as well as the buildings which constitute them. One criteria for evaluating the quality of life may be the assessment of one's access to direct sunlight and of its optimization through architectural form. The attention to solar benefits was highlighted by Knowles in 1980, who defined the concept of " solar envelopes " in which an individual building's maximum volume is calculated depending on its direct impact on neighbouring buildings' solar accessibility. This approach produces an empathetic architecture, conceived with consideration for pre-existing or potential developments and their inhabitants, yet maintaining the goal of creating a dense urban environment. Originally implemented on hand-built models, we presently propose a new software implementation of Knowles' concept, integrated into a well-known, pre-existing ergonomic Computer-Aided Architectural Conception (CAAC) program, and made possible due to the democratization of available 3D urban GIS models. This tool also incorporates factors such as building usage and the corresponding productive periods of direct solar irradiation for its occupants.