Simulation Tools

A simulation software or tool is usually based on the process of modelling a real situation with a set of calculations and assists one in understanding complex systems and decision-making. It helps to examine if the situation or condition changes, how the results would differ.
There are a number of simulation tools in Austrian market; here a few of them are introduced.

Transient System Simulation Tool (TRNSYS)

TRNSYS is a simulation programme primarily used in the fields of renewable energy engineering and building simulation for passive as well as active solar design. This tool is graphically based and used to stimulate the behaviour of transient systems. While most of the simulation tools are used for assessing the performance of thermal and electrical energy systems, TRNSYS can also be used to model other dynamic systems, such as traffic flow or biological processes.

The tool is made up of two parts:

  • The first part is an engine (kernel) which is able to read and process the input data. This engine also solves the model equations, determines convergence and plots system variables. The kernel provides utilities which can also determine thermophysical properties, invert matrices, perform linear regression and interpolate external data files.
  • The second part is a library of components. Each of these components models the performance of one part of the system. In the standard library around 150 models are included. They range from pumps to multizone buildings, wind turbines to electrolysers, weather data processors to economic routines. All of the models can be modified by the user. They can overwrite single components or write their own if needed.

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Thermal Analysis Simulation (TAS)

TAS is used for the simulation of climate-, facade- and energy concepts of the buildings. It is a dynamic simulation programme with a modular base. It is used for the planning and concept making of buildings and its green areas. The programme is able to copy real situations, statuses and variations. It delivers very precise prediction of the energy demand of a building. TAS is operating with two main modules, described below:

  • TAS Engineering: This module is used for thermal optimization of buildings. Impacts of air motion, solar radiation, warming and cooling of buildings can be simulated. With the data input from architects, the programme gives you detailed 3D models of buildings, where the mentioned impacts can be seen. The database for the calculations is very extensive. All different types of building elements with their specific U-values and data from more than 2500 weather stations are included in this database.
  • TAS CFD Ambiens: This module is an add-on for TAS Engineering. It is used to simulate the micro-climate of a room and its cosiness with a 2D flow analysis. This module is mainly used by building engineers.

More information is available under: (access in September 2016)

At this point it is worth mentioning that these tools are usually very cost-intensive and their prices are ranked up to a few thousand euros. Because of the high costs and the difficult handling, they will only be used by professional institutions.


The tools described here are used either by professionals (GEQ, GEQ-EBS) or can be used by spontaneous, non-professional, internet users (klimaaktiv-Coach, Energiesparcheck). All these tools are used to create a more or less accurate status quo reflection of personal or a building’s energy consumption. A different category of tools, so called simulation tools/software, can be used to portray possible changes over a period of time. To use this software, a high grade of technical and IT-knowledge is needed. The operation of the tools needs a lot of resources, meaning high calculating performance of the computer equipment.

Depending on the type of user and the intended use, there are many more tools which can be used. No matter which tool is chosen, the goals are common: The user gets more or less detailed information about his energy use or his energy behaviour. Through the results of the tools, users can be motivated to make either behavioural changes or even to set refurbishment actions. Hereinafter a final overview of all described tools.