It is demonstrated how Modelica™ is used in an application to develop models that are useful when solving real problems. Modelica is a new unified modeling language being developed in an international effort to promote object-oriented and non-causal modelling, and exchange of model libraries. The application is a heat exchanger where1 the media are liquids, typically water. This type of heat exchangers can be used for district heating of houses and for production of hot tap water. The model developed illustrates very nicely the power of Modelica.

A new language called Modelica TM for physical modeling is developed in an international effort. The main objective is to make it easy to exchange models and model libraries. The design approach builds on noncausal modeling with true ordinary differential and algebraic equations and the use of object-oriented constructs to facilitate reuse of modeling knowledge. There are already several modeling language based on these ideas available from universities and small companies. There is also significant experience of using them in various applications.

In recent years large glazed spaces has found increased use both in connection with renovation of buildings and as part of new buildings. One of the objectives is to add an architectural element, which combines indoor- and outdoor climate. In order to obtain a satisfying indoor climate it is crucial at the design stage to be able to predict the performance regarding thermal comfort and energy consumption. This paper focus on the practical implementation of Computational Fluid Dynamics (CFD) and the relation to other simulation tools regarding indoor climate.

This paper reports the background, status, and current outcome of a collaborative European Union sponsored international project, which aims to promote computer modeling and simulation of energy in buildings by creating hypertextbased self-Leaming course material and publishing it on the World Wide Web.

In modem livestock buildings the design of ventilation systems is important in order to obtain good air quality. The use of Computational Fluid Dynamics for predicting the air distribution makes it possible to include the effect of room geometry and heat sources in the design process. This paper presents numerical prediction of air flow in a livestock building compared with laboratory measurements. An example of the calculation of contaminant distribution is given, and the future possibilities of the method are discussed.