Calculation of shading factors on any facade or surface (e.g. a window) of a building, caused by the surrounding obstacles (other buildings, trees, walls, etc). The calculated shading factor can be tabulated either hour by hour, or as a monthly average. The definition of the geometry (studied building and surrounding) is done using a graphical and user-friendly interface.


shading factors, solar shading, building geometry



Expertise Required

Average level of PC computer practice; understanding of basic solar radiation concepts.


First distributed in September 1999.


Architects, engineers, researchers.


: The Scene Editor gives the user the possibility to define the complete geometric scene to be studied. The following elements can be introduced in the scene: parallelipipedic buildings with flat roof, rectangular buildings with one-pane tilted roof, rectangular buildings with two-pane tilted roof, polygonal-shaped buildings with flat roof, walls, trees. The trees can have an "activity period", specified as a month interval during which the shading is effective. The buildings can include windows and fixed solar protections (overhangs, sidefins). The roof can have an overhang part, whose size is specified independently for each facade.


The Three-Dimensional Display includes two possible views: a normal perspective view (the viewpoint can be chosen by the user) allows a visual check of the geometric scene; a parallel view from the sun's direction (the month, day, hour and the location can be chosen freely by the user) gives a visualisation of the building parts which are not in the direct sunlight. For the latter view, the user can also choose an hour by hour animation during one full day.
The Output User Interface provides the shading factors, either hour by hour or as monthly average values. The shading factors can be either output numerically, displayed as histograms, or written to a LESOSAI building file for taking the solar shading into account in the thermal calculation of a building.

Computer Platform

IBM-PC compatible, 486 or higher, Windows 95 or later, Windows NT 4 or later.

Programming Language

C, Visual Basic


The scenes are easy to define. The user can get very easily and in a short time both a 3-dimensional view of the scene and the shading factors. The calculation algorithm is versatile and can be used for virtually any shape, without any complex geometric considerations.


There is no possible connexion to a standard CAD package. The number of possible geometric shapes is rather limited. Only the complete site can be oriented accurately, the geometric elements (buildings, etc) cannot be rotated of an arbitrary angle. The calculation is accurate for the direct solar radiation but not for the diffuse component. The integration with the other software of the same family (LESOSAI, LESOCOMFORT, LESOCOOL, etc) is not yet operational. The 3-dimensional view is not very realistic.



Solar Energy and Building Physics Laboratory


Lausanne CH-0115


+41 (21) 693.45.46


: +41 (21) 693.27.22






CHF 200 or 100 (non-profit organizations), available in English, French and German language versions.