Office building of IBA AG in Fürth, Germany

Description of the application

To increase the room air comfort in the offices, a solar autonomous thermally driven chiller is installed. The chiller provides chilled water at a temperature level of approx. 9 °C for the operation of fan coils and chilled ceilings in the offices. The system is designed for top cooling. 

General description of the system

The system technology is a closed cycle chilled water system with a medium-sized absorption chiller. Heat is provided by a solar thermal system only, a gas boiler is installed, but used for space heating in winter. The heat rejection circuit of the chiller is connected to an open wet cooling tower. To avoid stagnation situations in the collector and to increase the collector efficiency, surplus heat of the collector is supplied to a nearby spa.

Central air-conditioning unit


closed cycle

Nominal capacity

30 kWcold

Type of closed system


Brand of chiller unit

EAW Wegracal SE 30

Chilled water application

chilled ceilings, fan coils


in fan coils

Heat rejection system

open wet cooling tower

Solar thermal

Collector type


Brand of collector

Solvis F-802-S, F-652-D

Collector area

87.7 m2 aperture

Tilt angle, orientation

25 °, south

Collector fluid


Typical operation temperature

86 °C driving temperature for chiller operation


Heat storage

3.7 m3 water

Cold storage

1.4 m3 water

Auxiliary heating support

gas boiler

Use of auxiliary heating system

for space heating; not used for chiller operation

Auxiliary chiller


System performance

The system went into operation in August 2007; no monitoring data are available at present. Due to the operation mode of solar autonomous cooling, high environmental benefits are expected compared to a conventional system solution with an electrically driven compression chiller.

System reliability and overall success of the installation

Due to the recent start of the system, no experience is available so far. The system is supported as a pilot installation in the frame of Solarthermie 2000plus, which is a federal funding scheme for large solar thermal applications. Monitoring of projects within this funding scheme is compulsory, thus, system experience will be made public available.

General information

Type of building  Office building
Location  Fürth, Germany (49°30’ North, 11° East)
In operation since  2007
System operated by  IBA AG
Air-conditioned area  920 m2


Collector area

Chiller unit
Collector area
Building view
Chiller unit

Clicking an image opens the gallery view.

Specific information

Further specific information about the system are included in the filled in technical questionnaire.



For more information on the project please feel free to contact:

Edo Wiemken