3D models can be used to quickly compare the shadow cast by, for instance, the existing roof-form with two possible options in extending a building.
3D modelling can be used to generate accurate information on the shadows that will be cast by a new development or extension. This information is specific to the latitude and longitude of the site in question. A number of images showing shadowing at typical times of year (usually the spring/autumn equinoxes and summer solstice) can be generated, as below.
The shadow information can be presented as an animation, as in this animation of a sun-dial, though this would be a very large file.