SOLARGE

GEWOBA AG


Bremen, Germany 

Multi-family house | 42 sqm installation 

+++ photo gallery +++

(changed on 2007 May 22)

Project summary · Technical description · Financing · Development · Downloads

Project Summary

Description

GEWOBA took part in a scheme "Retrofitting towards low energy in building stock" of the German Federal Ministry of Transport, Building Industry and Housing (BMVBW). The German energy agency dena implemented and coordinated the scheme on behalf of the authority. In addition, GEWOBA succeeded in also securing the support of the Energie-Konsens GmbH in Bremen for this project.

The project aims at implementing innovative and sensible building and retrofitting technologies, that allow refinancing. These measures are to become mainstream in the retrofitting sector.
A precondition for the choice of the object was the transferability of experiences made to other existing objcets of GEWOBA.

The installation of a solar energy control centre with solar collectors contributes to saving energy ressources. The solar energy is used for domestic hot water and space heating. The collectors are mounted in the form of a roof integration. They are fixed punctiformly on horizontal profiles. The piping is located in the attic, protected against the weather conditions.


 


Building

Type of building

Multi-family house

Number of dwellings, floors

approx. 27 users
18 dwellings
3 floors

Year of construction

1955

Total effective area (heated)

888 m2

Hot tap water consumption (measured/estimated)

264 m3/a

Whole energy consumption for heating purpose after CSTS implementation

84,000 kWh/a


System engineering

Year of construction of CSTS

2005

Type of collectors

Flat plate collectors

Thermal power

27 kWtherm.

Aperture area of collectors*)

39 m2

Buffer storage

0.65 m3

Hot tap water storage

0.3 m3

Total capacity of boilers with energy source

65 kW,
natural gas

Type of hot tap water heating

Centralised

Type of heating system

Centralised


Costs

Total cost solar system

90,000 Euro

Cost of the CSTS/gross area of collectors

2,143 Euro/m2

Subsidies

not available


Output

Output of solar heat**)

14.375 kWh/a
(amended on 2007 May 22)

Reduction of final energy***)

not available

CO2-emissions avoided

not available

Solar performance guarantee

No


*) 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

 

 


Dipl.-Ing. Architekt Stefan Fölsch, GEWOBA AG deputy
technical director:

"The conviction that the efficient use of the limited natural ressources represents a necessity is the stimulation for innovation and sustainablity. The optimal use of renewable energy sources is a logical result of this conviction."

 

 


Owner

GEWOBA AG
Stefan Fölsch
Rembertiring 27
D-28195 Bremen, Germany
Phone: +49 421 3672-364
Fax: +49 421 3672-283
foelsch(at)gewoba.de
www.gewoba.de


Operater

See owner

Top of page Project summary · Technical description · Financing · Development · Downloads

Technical description

 

 


Description of the CSTS

Year of construction of CSTS

2005

Thermal power

27 kWtherm.

Gross area of collectors

42 m2

Aperture area of collectors

38.55 m2 

Type of collectors

Flat plate collectors

Type of assembly

Roof intregrated

Orientation of collectors

South-East (-35°)

Inclination angle to horizon

32°

Freezing protection

Glycol

Overheating protection

Expansion vessel

Operation mode

Low flow

Use of CSTS for

Hot tap water heating, space heating

Buffer storage

0.65 m3
(1 storage tank, stratifying)

Hot tap water storage

0.3 m3 (1 storage tank )

Control of backup-system/CSTS

Shared control: Solvis Regierechner RIEcon MRC 20


Hot tap water system

Type of hot water heating

Centralised

Recirculation system

Yes

For decentralised systems:
The installation on the consumer site

./.

Size of storage for hot tap water

0.3 m3

Specification (if necessary)

./.


Space heating system

Type of heating system

Centralised

Number of boilers

1

Total capacity (power output) of boilers

65 kW

Capacity of each boiler (year of construction)

No. 1: 65 kW (2005)

Energy source

Natural gas

Type of boiler system

Condensing


Type of operation

Operator of the CSTS system

Self-operation

CSTS monitoring

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

Data accessible via internet

Yes

Scientific monitoring & follow up

Yes

Maintenance contract

Yes: the frequency of maintenance has not been settled yet. It will, however, still be agreed upon with the maintenance company, as soon as experience with the solar system is available.

Visualisation of the solar heat output

Yes: display on exterior wall


Yield of CSTS plant

Output of solar heat

not yet available

Origin of data

./.

Measuring point

./.

Reduction of final energy

not yet available

Origin of data

./.

Solar performance guarantee

No


Heat consumption

Whole energy consumption for heating purposes after CSTS implementation

84,000 kWh/a

Origin of data

Measured/estimated

Energy used for heating of

Hot tap water heating, space heating

Whole energy consumption for heating purposes before CSTS implementation

205,000 kWh/a

Total tap water consumption

not available

Hot tap water consumption

364 m3/a

Hot tap water temperature

54 °C

Cold water temperature

10 °C

 

 


Summary

 

Solar Control Centre with directing control computer RIEcon R36SEM
(see below)

 


 


 


 

  

 


Solar Control Centre with directing control computer RIEcon R36SEM 

 

The system described corresponds – in its design and its set-up – to advanced conventional house connection units. For the first time however, a complex control centre was installed for monitoring and controlling all components including the solar system.

The Solar Control Centre monitors the integrated heating circuit, a conventional and a domestic hot water heating and support of space heating.

The Solar Control Centre is a complete prefabricated unit, including cabling, with the following connections:

flow

<-->

district heating / boiler

return

<-->

district heating / boiler

flow

<-->

space heating

return

<-->

space heating

hot water

<-->

building feed-in

hot water

<-->

circulation

flow

<-->

solar circuit

return

<-->

solar circuit

feed-in of cold water

connection charging/discharging

solar buffer storage tank


The Control Centre and the directing computer RIEcon MR C 20 are integrated into the unit. These components are similar to those used for conventional house connexion units. Only components established in the heating installation sector are being used. Thanks to the compactness, the Control Centre only requires marginal space and its assembly of single components makes it easy to maintain. Apart from the conventional tasks of space and tap water heating, the Centre offers the following main functions:

1.

solar system:

switched off

conventional heating of tap water

buffer storage:

empty

conventional adjustment of circulation losses

space heating:

conventional

2.

solar system:

preheating

conventional supplementary heating of tap water

buffer storage:

charging

conventional adjustment of ciruclation losses

space heating:

conventional

3.

solar system:

preheating

conventional supplementary heating of tap water

buffer storage:

charging

conventional adjustment of circulation losses

space heating:

increased return flow of solar coverage, conventional supplement

4.

solar system:

full operation

charging of hot water, full coverage

buffer storage:

charging

solar adjustment of circulation losses

space heating:

increased return flow of solar coverage, solar supplement

All functions for domestic hot water and supplementary space heating mentioned above are accessible via the buffer storages in case of compliance of the regulation criteria.

 

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Financing and investment

Introduction

All in all, 90,000 Euros have been invested into the whole retrofitting measure including the solar system. The storage and heat exchanger represented the greatest assest. However, no specific information can be given on the financing and the subsidies on the solar system alone.


 


Financing of the CSTS

Form of financing

Purchase

Distribution in percentage

Due to total refurbishment no special figures for the CSTS available


Costs of solar materials

Total cost of solar system

90,000 Euro
(overall investment cost)

Detailed costs for

Collectors

21,000 Euro

Storage/heat exchanger

54,000 Euro

Backup heater

10,000 Euro

Installation

5,000 Euro


Operation costs of heating system

Increase of the operation cost after CSTS implementation

These information is not yet available and will be handed in later.

 


The financing of the solar systems was included in the budget for the whole retrofitting of the building including special insulation. Thus, no specific information can be given on the solar system. However, there are 4 sources of finance: KfW, Bremer Energiekonsens (Energy Agency), own ressources and the bank.




 


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Development & experiences

Qualitative aspects of the CSTS

Concerning the building, the dimension of the solar system is relatively large. However, no technical failures can be reported so far and thus, the overall assessment is positive. GEWOBA is fully content with its solar system, even if a higher use of hot tap water is desired. The dimensioning of the boiler is good, however, it disposes of a high pulsing and has not yet reached its coverage. This fact is not fully satisfying.

 


Experiences management

Experienced problems or failures?

No

Found solutions to these problems or failures?

./.


Financial effects / project performance

Project economically efficient?

No

Fiscal or other financial effects?

No

Effects on rental fees?

Yes


Experiences technical staff

Experienced problems or failures?

not available

Found solutions to these problems or failures?

not available

 

Summary of experiences / Notices to the project performance

GEWOBA applied for the participation of the object Steffensweg 97–101 in the financing scheme for the low energy retrofitting of building stock.

The objective has been an energetic challenging refurbishment of a building in stock and a reduction of the primary energy demand of about 80 %. The standard of the Energy Saving Ordinance (EnEV) was to be undershot by 50 % and a saving of CO2-emissions of 54 kg/(sqm·a) was to be reached.

The intended mix of measures included the solar installation from the very beginning. With initiation of the planning, the architect and the specialist engineers where brought together, in order to coordinate the design and the construction works. Here, GEWOBA was supported by the agency Plan_E.

Due to the sufficient dimensioning of the collector surface area, the preliminary planned airing with heat recovery could be dropped. This also saved some trouble for the tentants. Due to the good planning of the qualified contractor, the implementation went smoothly. Time schedule and budget were met. The solar system runs without faults.

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Downloads

SOLARGE_goodpractice_de_gewobaag_070522.pdf

this datasheet in printable PDF-format (changed on 2007 May 22)

1.8 M

gewobaag_scheme.pdf

the hydraulic scheme

867 K

Top of page Project summary · Technical description · Financing · Development · Downloads

Photo gallery