Sombrero 3.01

Sombrero 3.01 logo.

A PC-tool to calculate shadows on arbitrarily oriented surfaces. In designing both active use of solar energy (domestic hot water, photovoltaic) as well as passive solar architecture, shading and lighting of planes plays an important role. SOMBRERO provides quantitative results for shading of collectors or windows by buildings, overhangs, trees or the horizon. These results can be used either directly for visualization or as input for other thermal simulation programs. Screen Shots


Solar shading, solar radiation, building geometry, solar systems



Expertise Required

Basic knowledge about geometry and solar radiation


The users of SOMBRERO are distributed all around the world. The program is not restricted to a special country or region.


Architects, engineers for thermal simulation of buildings or solar plants


Three-dimensional objects are built up by their boundary planes. Up to 200 plane areas with 12 points each can be treated. Objects like houses and trees are predefined and described by parameters like height, width and position in space. Single planes are described by their vertex-points in the two-dimensional co-ordinate system related to the plane itself (in case of rectangles simply by their length and heigth) and positioned by indication of azimuth, elevation and origin in the three-dimensional space.

Time steps for simulation can be selected freely. Foliage of trees and reflection factors of the ground can be given as monthly schedules.

By means of the given input data, SOMBRERO creates a VRML (Virtaul Reality Modeling Language) file, which shows the shading situation in a three-dimensional model.


Output of SOMBRERO are values of the geometrical shading coefficient. The user can choose whether SOMBRERO calculates only the daily course of the shading coefficients as mean values for a month, or whether hourly data for every day of a month have to be calculated.

Computer Platform

The minimal system requirements for the work with SOMBRERO are: PC (468 DX or better), about 5 MB of free space on the hard disc, Windows 95 / NT, graphics board with resolution 800 x 600.

Programming Language



Easy to handle.





Group for Building Physics & Solar Energy / Fachge


University of Siegen / Universit�t - Gesamthochsch
Siegen D-57068


+49 (271) 740-3817


+49 (271) 740-3820




A free demo-version of SOMBRERO can be downloaded from the web site of the Group for Building Physics & Solar Energy at the University of Siegen with the address This demo-version is fully operational for 10 days after its first installation. For unlimited use of the program one needs to purchase a license for 200 � (= 200 US$).