Eggenberger Allee

Graz, Austria

Multi family house | 120 sqm installation

Project summary only


Project summary · Technical description · Financing · Development · Downloads

Project Summary

This condominium consists of 52 dwellings, with an average area of 50 m² to 95 m² and in addition some offices.
The building has a centralised heat supply system which is fed by a solar thermal system and a natural gas condensing boiler.
120 m² of serial connected collectors significantly provide this building during the summer month.



Type of building

Multi family house

Number of users / dwellings, floors

52 dwellings
+ business area

Year of construction


Total effective area (heated)

approx. 3,400 m2

Hot tap water consumption (measured/estimated)

2,555 m3/a (7 m3/d)

Whole energy consumption for heating purpose after CSTS implementation

527,000 kWh/a

System engineering

Year of construction of CSTS


Type of collectors

Flat plate collectors

Thermal power

76 kWtherm.

Aperture area of collectors*)

108 m2

Buffer storage

9.5 m3

Hot tap water storage


Total capacity of boilers with energy source

225 kW, natural gas

Type of hot tap water heating


Type of heating system



Total cost solar system

61,800 Euro

Cost of the CSTS / gross area of collectors

515 Euro/m2


not available


Output of solar heat**)

51,120 kWh/a

Reduction of final energy***)

60,140 kWh/a

CO2-emissions avoided

16 t CO2/a

Solar performance guarantee


*) Aperture area = light transmitting area of the front glass
**) measured, between storage and piping to taps (solar system output)
***) related to the measured output mentioned before



Neue Heimat, gemeinnützige Wohnungs- und Siedlungsgenossenschaft in Steiermark GmbH, Graz


Noch offen


Architekt Riepl, München


TB Pickl & Partner, Graz


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Annotation to Good Practice examples from Austria

Concept definition and monitoring as well as system adjustment of the presented project have been done within the framework of "OPTISOL – accompanied monitoring in demonstration projects for optimised and standardised solar systems for residential buildings", financed by the Austrian Federal Ministry of Traffic, Innovation and Technology ("Haus der Zukunft"), by the Austrian Federal Ministry of Economics and Labour and the Federal State Steiermark.