SOLARGE

Strählerweg

Karlsruhe, Germany

Single-family detached house | 125 sqm installation

 


Project summary · Technical description · Financing · Development · Downloads

Project Summary

Description

Constructed in 1969, the building showed an annual need in space heat of 118.000 kWh due to a reactivated swimming pool, which corresponds to a consumption of 11.000 litres of oil.

A low-level standard in heat dissipation is achieved by an additional insulation of the flat roof by 16 cm (λ= 0.030W/mK), insulation of the visible concrete walls of the basement by vacuum insulation panelling (λ= 0.0042 W/mK), installation of a cover for the swimming pool, glassing of important windows with special insulation glass, insulation of the walls of loggias and of heat bridges with mineral wool and plaster as well as application of exterior thermal collector (Sonnenkraft IFK, tailor-made) on the exposed fasades of all four walls of the upper floors. This is all possible through the low energy figures of exterior walls which have been insulation with collectors and vacuum panelling (U= 0.15 … 0.19 W/sqmK).

The KfW 40-level in primary energy is achieved through the additional installation of a brine pump.

In addition, the exploitation of the normally unused remaining solar warmth in the storage tanks contributes to a more efficient solar system as well as a better figure of merit.

The solar system works as a source for hot water, also covering the swimming pool, supports the heat pump and supplies a highly efficient insulation of face elements.

The electrical energy which is neccessery for the operation for the heat pump is supplied by a photo-system 4 kWp (Mitsubishi thin-film module) which is installed on the flat roof.



 


Building

Type of building

Single-family detached house incl. architectural office and therapeutical surgery

Number of dwellings, floors

3 dwellings
2 floors

Year of construction

1969 (2003–2006)

Total effective area (heated)

320 m2

Hot tap water consumption (measured/estimated)

36 m3/a (calculated)

Whole energy consumption for heating purpose after CSTS implementation

27,000 kWh/a


System engineering

Year of construction of CSTS

2004

Type of collectors

Flat plate collectors

Thermal power

60 kWtherm.

Aperture area of collectors*)

85 m2

Buffer storage

2.0 m3

Hot tap water storage

./. 

Total capacity of boilers with energy source

14 kW,
heat pump, run by PV

Type of hot tap water heating

Centralised

Type of heating system

Centralised


Costs

Total cost solar system

85,578 Euro

Cost of the CSTS/gross area of collectors

685 Euro/m2

Subsidies

2 %


Output

Output of solar heat**)

26,000 kWh/a

Reduction of final energy***)

25,000 kWh/a (data from heat pump not yet included)

CO2-emissions avoided

32 t CO2/a

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

 

 


Hinrich Reyelts, holder of architecture firm Reyelts:

„In order to make something possible arise, the impossible has do be tried again and again.“

[Hermann Hesse, German writer]

 

 


Owner

Claudia Wende-Reyelts
Strählerweg 117
76227 Karlsruhe, Germany
Phone: +49 721 495140
Fax: +49 721 9415869
buero(at)reyelts.de
www.reyelts.de


Operater

See owner

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Technical description

 


Description of the CSTS

Year of construction of CSTS

2004

Thermal power

60 kWtherm.

Gross area of collectors

125 m2

Aperture area of collectors

85 m2 

Type of collectors

Flat plate collectors

Type of assembly

Facade

Orientation of collectors

East (-105°), South (-15°), West (+75°)

Inclination angle to horizon

90°

Freezing protection

Glycol

Overheating protection

Expansion vessel

Operation mode

Variable

Use of CSTS for

Hot tap water heating, space heating, swimming pool heating

Buffer storage

2.0 m3 (2×1.0 m3)

Hot tap water storage

./.

Control of backup-system/CSTS

Shared control
first: increase of return temperature at heating oil boiler;
new configuration brine heat pump: supply of basic load, heat pump stratifies in the upper part of buffer storage


Hot tap water system

Type of hot water heating

Centralised

Recirculation system

No

For decentralised systems:
The installation on the consumer site

./.

Size of storage for hot tap water

2.0 m3

Specification (if necessary)

Combined, volume hot tap water: 0.2 m3


Space heating system

Type of heating system

Centralised

Number of boilers

1

Total capacity (power output) of boilers

14 kW

Capacity of each boiler (year of construction)

No. 1: 14 kW (2006)

Energy source

Electricity (PV-system)

Type of boiler system

Brine heat pump


Type of operation

Operator of the CSTS system

Self-operation

CSTS monitoring

Yes: output of solar heat. Resol Data-Log by operator (=planner),
by Sonnenkraft SKSRPC and continuous
personal readings.

Data accessible via internet

Yes

Scientific monitoring & follow up

Yes

Maintenance contract

Yes: once a year

Visualisation of the solar heat output

No


Yield of CSTS plant

Output of solar heat

26,000 kWh/a

Origin of data

Measured and calculated

Measuring point

Between collector and storage

Reduction of final energy

25,000 kWh/a

Origin of data

Design and measured (volumetric flow meter)

Solar performance guarantee

No


Heat consumption

Whole energy consumption for heating purposes after CSTS implementation

27,000 kWh/a

Origin of data

Measured/estimated

Energy used for heating of

Hot tap water heating, space heating, swimming pool heating

Whole energy consumption for heating purposes before CSTS implementation

96,500 kWh/a

Total tap water consumption

259 m3/a

Hot tap water consumption

36 m3/a

Hot tap water temperature

45 °C

Cold water temperature

10–12 °C

 

 


Summary

The three-sided system regulates the stratified loading of the buffer stores, the swimming pool and the additional heating of hot water with two three-circuit control systems (Sonnenkraft SKSR3).
The extraction of drinking water (warm) is effected by a fresh water module.
The simulated returns of the solar system amount to approx. 50,000 kWh/a, the measured and utilized returns amount to approx. 12,500 kWh/a without heat pump. With a heat pump control in the described form it amounts to the double return.

The saving of heating oil before the switch-over of the heating systems to the operation of heat pumps amounts to approx. 3,000–3,500 litres/a according to a saving of 80 %.




Planner 

Architekturbüro Reyelts
Dipl.Ing. Hinrich Reyelts, Architect
Strählerweg 117
76227 Karlsruhe, Germany
Phone: +49 721 9415868
Fax: +49 721 9415868
buero(at)reyelts.de
www.reyelts-architekten.de

 

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Financing and investment

Introduction

Total costs of the solar systems including the renovation of the fasade and of the roof connection (sheet metal works): 107.572 EUR.


 


Financing of the CSTS

Form of financing

Purchase

Distribution in percentage

77 %


Costs of solar materials

Total cost of solar system

85,578 Euro

Detailed costs for

Planning / Engineering

1,103 Euro

Others (valves, pumps, expansion vessels)

2,226 Euro


Operation costs of heating system

Power cost for pumping

211 Euro/a

Maintenance cost

311 Euro/a

Monitoring cost

58 Euro/a

Total operation cost

580 Euro/a

 



BAFA: no subsidies because of the swimming pool
Stadtwerke Karlsruhe: 2,000 EUR subsidies
KfW (program 130): 80.000 EUR soft loan, pay-back amount: 80 %


Total costs including other refurbishment measures: 107,572 EUR


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Development & experiences

 

Summary of experiences / Notices to the project performance

A project of this kind requires dedication, conviction, patience and positive cooperation of everybody involved.

Extra costs cannot be avoided because of missing comparison data.

However, the profits can be much higher than expected, as we have achieved here.


 


Experiences management

Experienced problems or failures?

Yes: bad installation of temperature sensors, bad adjustment of back-up heating, control

Found solutions to these problems or failures?

Yes: sensors installed, back-up heating via solar control and time, high impact of individual control adjustment by monitoring


Financial effects / project performance

Project economically efficient?

Yes

Fiscal or other financial effects?

Yes: Reduction of whole tax load by investments for refurbishment in commercial premises

Effects on rental fees?

No


Experiences technical staff

Experienced problems or failures?

Yes: as above plus fouling of inner side of glasses

Found solutions to these problems or failures?

Yes: glasses removed, cleaned and reinstalled

 


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

Downloads

SOLARGE_goodpractice_de_straehlerweg.pdf

this datasheet in printable PDF-format

1.6 M

straehlerweg_scheme.pdf

the hydraulic scheme

790 K