Lacasa can be compared to a library of building blocks of buildings and technical installa­tions, ordered in "Classes" and "Subclasses", and one which allows further development and additions. Each Block models a real building block, such as walls, windows, heating units, pipes or controls. When you click on a block, a dialog window pops up, allowing the user, for example, to select the geometry of a wall or look at its construction (see Figure 1). The input parameters can be either given as numbers, or alternatively as freely defin­able variables. The latter feature is particularly interesting when using the models for an optimization procedure.

In order to account for the needs of design engineers as well as scientists, Lacasa offers the possibility to select among different applications ("ENGINEERING", "SCIENTIFIC", and various forms of data administration), just by using the mouse. For further details, an

online help can be activated from the input mask of each block, and printed out if needed (PDF file). The building-blocks structure of Lacasa propagates through all levels of the li­brary. Its intuitive and uniform operation control makes getting started easy, and vastly fa­cilitates implementing new models.

Lacasa was developed under Windows2000 using MATLAB-Simulink Version 13, but will work under Linux as well. This requires the existence of a license for MATLAB-Simulink for Linux, and recompiling all C-sources with the appropriate Linux compiler. All other files are in principle Linux-compatible. At the present stage of development, Lacasa consists of 740 files which require 40 MB of disk space. It is worthwhile pointing out that 82% of these files are aimed at user-friendliness, as for example the easy data management and the graphi­cal user interface. The computation models needed for simulations and the online-help claim only 8.2% and 8.8%, respectively, of Lacasa’s total amount of data.

4 Database

All the data concerning the characteristics of the components and materials used in the application "ENGINEERING" are saved as text data files. The data management is such, though, that the user does not need to access the text files directly. Lacasa possesses a pre-processor for weather information, which can read any file, structured in columns,

containing raw weather data, automatically filling in the missing weather elements and generating a data set with 21 weather elements, formatted according to the requirements of Lacasa.