Solar-Institut Julich / Fachhochschule Aachen Heinrich-MuRmann-StraRe 5, 52428 Julich Tel.: 02461 / 99 -3532, Fax: 02461 / 99 -3570 www. sij. fh-aachen. de, info@sij. fh-aachen. de

K. Schwarzer, M. Werner, T. Hartz, L. Aliaga 1 Motivation

Experience with 20 different commercial simulation programs has been gathered at the Solar Institute in Julich. On the one hand, simulation programs with operator-friendly user interfaces for the design of standard systems are currently available. The advantages here are the short training period required and low price, but with the disadvantage of limited flexibility. On the other hand, there are programs available which offer flexibility in nearly all technical equipment concepts. The disadvantages here are the complicated operating in­structions which often lack clarity, and the long training period required.

Given this background, in 1996 the Solar Institute in Julich decided to develop computer models for solar thermal and conventional heating systems, using MATLAB-Simulink® /1/. At about the same time, and in the same Institute, the basics of a building model, which is the foundation of the toolbox "Lacasa” presented here, were established within the frame­work of both a dissertation and the project Solar-Campus Julich /2/.