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TABSDesign: a free tool for the sizing and control of thermally activated building systems (TABS)

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Overview of the input data related to the building envelope

The free HVAC design tool “TABSDesign” is a computational aid for the sizing and control of thermally activated building systems (TABS). It supports and executes HVAC design of TABS through the unknown-but-bounded (UBB) planning process described in the "TABS Control" manual.


How it works

In contrast to the conventional iterative design method of TABS, which is based on iterative dynamic model simulation studies, this tool presents a simplified approach which results in a more straight-forward calculation process. It is based on lower and upper bounds for the heat gains that should be estimated within the design process.


The design tool also shows the limits in certain cases of TABS application alone and points out when additional auxiliary heating or cooling devices should be installed. Other decisions like zoning of different rooms can be made by the HVAC designer using the decision tree diagram provided by the UBB-method. The sizing is less time consuming and enables more insight into the potential of TABS. The design tool provides results that can be used directly as the initial setting for the control strategies of the TABS.



The output of the tool consists mainly of a series of heating and cooling curves (supply water temperature setpoints plotted against outside air temperature) for different heat gain spans and associated room geometries, as well as the sizing of cold and heat generation (rated power) of the primary and secondary heating and cooling system whenever one is required. Basic control strategies are also derived in case an auxiliary system is needed.


Additional information

The Excel based tool shows the information in German and requires the add-in MATLAB® Runtime Compiler (MCR). Different versions are available depending on the operative system (Windows 7 version was released in 2013), with or without the MATLAB® Runtime Compiler, and can be downloaded from this page


The tool was developed by Siemens Building Technology Group, Swiss Federal Laboratories for Materials Testing and Research, and Lucerne University of Applied Sciences and Arts.