OPTISOL - Demonstration objects accompanied by measurement techniques for optimised and standardised solar systems in the construction of residential buildings for several families

The implementation of optimised solar heat supply systems in the construction of residential buildings for several families within the framework of an in-depth test.

Content Description




The know-how transfer project OPTISOL was carried out as a wide range of tests with building associations and especially assisting planers and executive companies (HVAC planers, architects, installer and system operators) as target groups. Ten optimised solar-supported heating networks for multi-storey residential buildings were implemented with scientific monitoring and support. The emphasis lay not only on optimising the solar thermal system as a single component, but more to optimise the entire energy supply system and to define new quality standards for solar-supported energy supply systems. At the same time, it was shown that solar-supported heating networks (erected with state-of-the-art technology) throughout enable a promising operation, also measured with economical criteria. 10 concrete construction projects, which were to be supported throughout their entire planning and implementation phases (planning audits, based on integral approach, support during the proposal and contract procedures, entire construction site appointments during the construction phase as well as assistance during the initial operation) in the framework of OPTISOL were chosen from more than 20 interested building associations.

The building projects which were chosen to be assisted within OPTISOL range from housing estates with 6 apartments and semidetached buildings to multi-storey residential buildings with more than 60 apartments in combination with business offices. The largest solar thermal system includes 240 m² collector area and the smallest system 30 m². In the framework of OPTISOL was a total of just under 1,200 m² collector area and about 100 m³ storage tank volume for the heat supply of 402 apartments installed. The elaborated and implemented solar-supported heating networks all based on a 2-pipe-system with a decentralised domestic hot water preparation in the apartments with the means of the so called "apartment units".

A further central project emphasis was the monitoring of the demonstration buildings during a defined period of time. All heat flows in eight buildings could be measured over at least an entire operating year during the project time frame. The so called "optimisation phase" was established as a central instrument to increase the total system quality. All system temperatures, which were registered by the monitoring system, were analysed during the first operation weeks. Thereafter were optimisation measures initialised, based on the monitoring results. The experiences from the project showed that otherwise undiscovered weak spots could be found and serve as base for the optimisations steps. It should be mentioned that the weak spots did not at all only apply to the solar thermal systems, but in equal amount to the conventional heat supply system, to the overall plant controller or also to the distribution system. All these weak spots have a negative effect on the reachable annual system efficiency of the entire heat supply system but remain unnoticed over years and are compensated through higher primary energy input. The experiences from the optimisation phase in the OPTISOL project clearly show that a big part of the weak spots can be noticed with little effort in a system analyses during the first two operating months and that the client has no added costs for the adjustments within this time frame of the warrantee.

After the "optimisation phase" the monitoring merged to "routine supervision" in the OPTISOL project. It was especially seen to that the solar thermal system was connected with the central for automatically default messages of the conventional heating system. The hereby attained monitoring results show an extremely satisfactorily operating behaviour by all the analysed solar-supported heat supply systems.

The predefined performing guarantee value in the building contract (all projects fixed to 350 kWh/m²a) could practically be exceeded in all cases. Although the solar fraction of the total energy demand (domestic hot water and space heating) in most of the multi-storey residential buildings lie between 12 and 20%, the specific solar fraction reach the remarkable yearly value of between 360 kWh/m² and 440 kWh/m² gross collector area. The achieved annual system efficiency reach excellent values between 70 and 86%.

Further, the results from OPTISOL show that solar-supported heating networks of this quality standard are absolutely interesting also from an economical point of view. The analysed systems were shown to reach a dynamically calculated payback time between 10 and 20 years, depending on the substituted heating system and the granted subsidy. This under the consideration of a forecast life time of minimum 25 years.

A planning handbook, "Solar-supported heating networks multi-storey residential building - a planning handbook with a holistic approach" (95 pages) could be compiled and printed based on the reached project results.

Also in the area of housing subsidy could an important step be taken within the frameworks of this project. The activities and results of this project were determining to the fact that solar thermal systems in new erected residential buildings will be future prerequisite to receive subsidies in the federal state of Styria.

More than 160 participants at the two know-how-transfer events carried out within the project framework clearly show the interest in this technology and the reached goals of OPTISOL.

Project Partners

Project manager:

Ing. Christian Fink
AEE INTEC, Arbeitsgemeinschaft ERNEUERBARE ENERGIE, Institut für Nachhaltige Technologien


Ing. Christian Fink
AEE INTEC, Arbeitsgemeinschaft ERNEUERBARE ENERGIE, Institut für Nachhaltige Technologien
Feldgasse 19, A 8200 Gleisdorf
E-Mail: c.fink@aee.at