Some Aspects of Thermal and Radiation Flows Modelling in Buildings Using Modelica

Efficient use of energy in buildings is very important. Special attention is given to the use of passive energy resources as the costs for heating and cooling can be significantly reduced and living conditions at the same time improved. Modelling of thermal and radiant flows and illumination is very important in this area and so many models with different aims and complexity were developed in the past. Traditional models have a significant lack of object orientation which represents an important disadvantage, because it is difficult or sometimes even impossible to reuse model components. This paper deals with some activities about a simulator which models thermal and radiation flows in buildings. It was originally developed in Matlab/Simulink environment. With the reimplementation in object-oriented Dymola Modelica environment the quality of simulator was significantly improved in different aspects. However, since distribution of radiation flows is mostly geometrical problem, the reusability is not gained implicitly by using Modelica as it is when using models described by DAE. Additional efforts were needed to make components fully reusable. The proposed solutions significantly increased the possibilities for more complicated building structures modelling.