Energy-efficient buildings

The working group Energy Efficient Buildings deals with the development and analysis of energy supply solutions for buildings and building networks. The content ranges from the development and numerical modelling of individual building technology components to the conceptual design, simulation and optimisation of complex energy systems for the thermal conditioning of buildings and for large districts.

R&D focus

Numerical simulation of buildings and technical building systems

A tool used in many projects is thermal plant and building simulation. With the simulation tools used (currently. IDA ICE or TRNSYS), the transient thermal behavior of buildings is mapped and analyzed in detail and geometry-based. Building technology systems are mapped according to the actual interconnection using single-component models (boilers, heat pumps, solar collectors, storage tanks, pipelines, valves, etc.) and modeled including the control system. With the help of the models, different tasks can be processed:

  • Determination of heating and cooling requirements
  • Calculation of room temperatures, humidity, assessment of comfort
  • Evaluation of different construction variants and building designs
  • Development of control strategies (ventilation, shading, building technology, etc.)
Examples of building models in IDA ICE & view of a technical building system simulation in the user interface of TRNSYS

Urban Energy Concepts and Grids

One focus of the working group is the dynamic modelling and analysis of energy systems for districts of thermal supply systems. For this purpose, solutions have been developed in recent years that make it possible to consider all relevant components of district energy supply systems (energy generation, distribution grid, consumers) in the simulation in high spatial and temporal resolution.

1 Visualization of the heat demand of a supply area (Nageler et al., 2017)
2 temperature distribution in a district heating network (Nageler et al., 2019)

Model development

If necessary, component models that are not available in the commercial software packages used or are not available in sufficient detail are created by the company itself. For example, a semi-physical heat pump model (Type 887), various latent heat storage models (Type 840, Type 842 and the ice storage model Type 843) have been developed for the TRNSYS software in recent years.

Heat pump cycle (economizer circuit) in the T-h diagram (Type 887)

Experimental analyses in the laboratory and in the field

Experimental work includes the development of functional models and the metrological analysis of building technology components in the laboratory and test buildings as well as long-term measurements/monitoring on field systems.

Experimental setup for latent heat storage in a supercooled salt hydrate
Thermally identical test buildings on the campus of Graz University of Technology


P. Nageler, G. Zahrer, R. Heimrath, T. Mach, F. Mauthner, I. Leusbrock, H. Schranzhofer, C. Hochenauer, Novel validated method for GIS based automated dynamic urban building energy simulations, Energy, Volume 139, 2017, Pages 142-154, ISSN 0360-5442,

P. Nageler, R. Heimrath, T. Mach, C. Hochenauer, Prototype of a simulation framework for georeferenced large-scale dynamic simulations of district energy systems, Applied Energy, Volume 252, 2019, 113469, ISSN 0306-2619,



Energy-efficient buildings

Dipl.-Ing. Dr.techn.
Thomas Mach


Mo-Fr: 09:00-12:00 Uhr
Raum: MB05 010 (5.OG)
Tel.: +43-316-873-7301
Fax: +43-316-873-7305