Schmochtitz, Germany

Educational centre | 79 sqm installation

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Project summary · Technical description · Financing · Development · Downloads

Project Summary


The Bishop Benno House in Schmochtitz is the central educational institution of the diocese Dresden Meissen.
Within the framework of development a former barn, a solar thermal system for hot water heating for three buildings (barn, land house, main house) was established on the new covered roof.

Objectives of this measure were reducing environmental impacts, architectonical integration on a listed building and a concrete visualisation to the visitors. About 7.5 tons of carbon dioxide will be avoided each year due to the Bishop Benno House’s solar thermal system.



Type of building

Eductional centre

Number of dwellings, floors

75 rooms
11 dwellings

Year of construction


Total effective area (heated)

./. m2

Hot tap water consumption (measured/estimated)

42 m3/a

Whole energy consumption for heating purpose after CSTS implementation

468,000 kWh/a

System engineering

Year of construction of CSTS


Type of collectors

Flat plate collectors

Thermal power

48 kWtherm.

Aperture area of collectors*)

69 m2

Buffer storage

4.0 m3

Hot tap water storage

0.7 m3

Total capacity of boilers with energy source

495 kW,
heating oil

Type of hot tap water heating


Type of heating system



Total cost solar system

55,758 Euro

Cost of the CSTS/gross area of collectors

706 Euro/m2


50 %


Output of solar heat**)

23,360 kWh/a

Reduction of final energy***)

27,500 kWh/a

CO2-emissions avoided

7.5 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



Dr. Peter-Paul Straube, Bishop Benno House's headmaster:

"Upcoming refurbishment of our barn's roof initiates considering integrated solar collectors. Thus keep down installation costs for the solar system. Due to the solar thermal system Bishop Benno House saves fossil fuels and visitors are shown a concrete use of alternative energy systems."


Herr Dr. Peter-Paul Straube
Schmochtitz 1
D-02625 Bautzen, Germany
Phone: +49 35935 22-0
Fax: +49 35935 22-310


See owner

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Technical description



Description of the CSTS

Year of construction of CSTS


Thermal power

48.3 kWtherm.

Gross area of collectors

79 m2

Aperture area of collectors

69 m2 

Type of collectors

Flat plate collectors

Type of assembly

Roof integration

Orientation of collectors

South-East (-18°)

Inclination angle to horizon


Freezing protection


Overheating protection

Expansion vessel

Operation mode

Low flow

Use of CSTS for

Hot tap water heating

Buffer storage

4.0 m3
(2×2×1.0 m3, barn and cottage each with two storages)

Hot tap water storage

0.7 m3 (2×0.35 m3)

Control of backup-system/CSTS

Shared control: heat-exchanger set (Viessmann)

Hot tap water system

Type of hot water heating

Decentralised (supply per building)

Recirculation system


For decentralised systems:
The installation on the consumer site

Hot water tanks

Size of storage for hot tap water

0.7 m3 (2×350 l)

Specification (if necessary)


Space heating system

Type of heating system


Number of boilers


Total capacity (power output) of boilers

495 kW

Capacity of each boiler (year of construction)

No. 1: 285 kW (1999)
No. 2: 80 kW (1992)
No. 2: 130 kW (1992)

Energy source

Heating oil

Type of boiler system

Low temperature

Type of operation

Operator of the CSTS system


CSTS monitoring

Yes: solar radiation, output of solar heat,total water consumption

Data accessible via internet


Scientific monitoring & follow up


Maintenance contract

not available

Visualisation of the solar heat output

Yes: monitor in foyer

Yield of CSTS plant

Output of solar heat

23,360 kWh/a

Origin of data


Measuring point

Between collector and storage

Reduction of final energy

27,500 kWh/a

Origin of data

Calculated (University of Dresden)

Solar performance guarantee


Heat consumption

Whole energy consumption for heating purposes after CSTS implementation

468,000 kWh/a

Origin of data


Energy used for heating of

Hot tap water heating

Whole energy consumption for heating purposes before CSTS implementation

491,360 kWh/a

Total tap water consumption

770.88 m3/a

Hot tap water consumption

42.34 m3/a

Hot tap water temperature

64 °C

Cold water temperature

16 °C




The first challenge was to find a planner who was able to develop such a system for supporting heat to three buildings. The planner was in charge for the complete project development including dimensioning and tendering. Installation of collectors was done at same time of roof the barn. Technical University of Dresden has done the monitoring of the solar thermal system. Engineering a solar thermal system needs to consider the whole energetic concept as well as the exact heat demand.




Ingenieurbüro Dr. Scheffler & Partner GmbH
Herr Dr. Scheffler, Herr Herrmann
Pfaffensteinstr. 1c
D-01277 Dresden, Germany
Phone: +49 351 25469-0
Fax: +49 351 25469-18


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Financing and investment

From the economic point of view the solar thermal system pays by reducing the amount of 2,750 litres of oil each year. This means savings of 1,513 EUR each year at current oil prices of 0.55 EUR per litre.


Financing of the CSTS

Form of financing


Distribution in percentage

50 %

Costs of solar materials

Total cost of solar system

55,758 Euro

Detailed costs for


15,987 Euro

Storage/heat exchanger

13,460 Euro


7,555 Euro


10,316 Euro

Planning / Engineering

8,440 Euro

Operation costs of heating system

Increase of the operation cost after CSTS implementation

Increase due to installation of additional pumps, no figures available


Special Note for Subsidy Systems
Within the framework "300 congregations for solar energy" the German environment foundation "Deutsche Bundesstiftung Umwelt" has supported this project with 28,000 EUR.

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Development & experiences

Summary of Experiences/ Notices to the project performances

In 2001 the solar system failed during three weeks due to a breakdown of the control computer. Since then the system is running faultless. Five years after the installation the surrounding of collectors' roof integration has to be repaired caused of leakages. Anyway, it was the right decision integrating collectors in the roof in comparison to a solely roof top installation.

Experiences management

Experienced problems or failures?

Ves: due to computer breakdown in 2001 no control; no problems since then

Found solutions to these problems or failures?


Financial effects / project performance

Project economically efficient?


Fiscal or other financial effects?


Effects on rental fees?


Experiences technical staff

Experienced problems or failures?


Found solutions to these problems or failures?





Kallweit Solartechnik
Herr Kallweit
Altenzeller Straße 29
D-01069 Dresden, Germany
Phone: +49 351 47185-59
Fax: +49 351 47185-65


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this datasheet in printable PDF-format

1.1 M


hydraulic scheme

215 K

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