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Integrated Neighbourhood Energy Concept, Karlsruhe-Rintheim

EnEff:Stadt - Forschung für die energieeffiziente Stadt

Aerial view of the Karlsruhe-Rintheim residential neighbourhood.

© Volkswohnung GmbH

Settlement summary

Project status Projektstatus: Phase 3Realisation
Location of local community Stadt Karlsruhe, 76137 Rintheimer Feld, Regierungsbezirk Karlsruhe, Baden-Württemberg
Developer, organizer Volkswohnung GmbH Karlsruhe
Settlement Mixture of high-density linear apartment blocks and high-rise apartment complexes
Utilisation type General living
Settlement size 210.000 m²
Gross floor area (according to DIN 277) before refurbishment 18.110 m²
Gross floor area (according to DIN 277) after refurbishment 19.910 m²
Residential space before refurbishment 79.593 m²
Residential space after refurbishment 87.000 m² (abhängig vom Neubaukonzept)
Energy supply area ca. 1.200 m²
Number of accomodation units before refurbishment 1.188
Number of accomodation units after refurbishment 1.290 (abhängig vom Neubaukonzept)
Age structure Construction phase between 1954 and 1974
State of construction and refurbishment Poor - requires considerable refurbishment
Heating system Gas central heating system, partly individual stoves (coal), construction of local heating system ist started
Ownership structure Of the 34 residential buildings currently in the neighbourhood, 30 belong to Volkswohnung Karlsruhe, which will construct 4 more buildings; the other 4 residential buildings belong to private owners. The City of Karlsruhe operates the 2 schools.
Project themes

Project description

Community and neighbourhood

The City of Karlsruhe is participating in the European Energy Award® and is currently preparing initial eea certification. At the same time, an urban energy concept was developed in 2009 in the form of a catalogue of energy and climate protection measures, primarily using existing resources. The catalogue of measures was completed by a Karlsruhe Climate Protection Concept working group in six months (from August 2008 to July 2009), under the direction of the Environmental Protection Authority and incorporating IFEU Heidelberg.
In part, the Rintheim neighbourhood is a typical post-war large apartment complex, conceived as rapidly available and low-cost accommodation for the needs of the period with contemporary technical resources. The other part of the neighbourhood was built in the sixties and seventies, with improved heating technology (heating centres) and different architecture (high-rise buildings) – but not significantly better built in terms of energy. The neighbourhood has limited amenities (mini-supermarket, hairdresser, kiosk). As a result of the proximity to the inner city (1.5 km) and the excellent local public transport connections, this has only a minor effect on the standard of living. The neighbourhood concept investigated possible improvements with regard to the needs of future residents.

Project objectives and measures

As a result of the age of the buildings and the obsolete technical quality, the buildings need comprehensive renovation. In order to increase the standard of living and the value of the neighbourhood overall, the refurbishment is to incorporate all buildings (owned by Volkswohnung) where possible, as well as the area surrounding the buildings, making the neighbourhood more attractive, both visually and in terms of leisure activities. In conjunction with this, a sustainable increase in value, both for residents and the remaining local investors in addition to Volkswohnung is also planned. For this purpose, the expected future needs of the residents must be considered and an overall concept developed. The energy quality of the buildings must also be improved so that a certain independence from the future developments in the energy sector (e.g. energy prices) can be achieved.
In the planning phase, an overall concept for the neighbourhood is to be developed which will allow a major improvement in energy terms, while maintaining the level of rent including bills of the Volkswohnung tenants. To do so, the ideal combination of measures, which result in an ideal economic level of energy savings and efficiency in energy supply, must be found. While implementing the measures, an energy management system must be put in place to allow subsequent system operation to be monitored and continuously optimised.

At the beginning of the implementation phase between summer 2009 and spring 2010, two buildings with 30 accommodation units each will be refurbished to test the state-of-the-art or currently available technical innovations and evaluate measurements and calculated simulations, and based on this experience, to use select innovations in the buildings to be refurbished subsequently without scientific supervision.

Energy balance

Of the 34 existing residential buildings in the neighbourhood, 30 belong to Volkswohnung; there are four additional building sites for blocks of flats, with a total of 120 apartments, which were demolished in 2004. The municipal utility company of Karlsruhe provided the gas and electricity consumption data required to issue the energy consumption certificates, for the period from 2005 to 2007 for the properties owned by Volkswohnung. This comprises 20 buildings with gas central heating systems containing 755 accommodation units and 50,846 m² of residential space, and 10 buildings with individual gas-fired central heating systems containing 226 accommodation units and 13,870 m² of residential space. The specified heating energy requirements were calculated based on an assumed annual average boiler efficiency of 88 % and a hot water requirement of 22 kWh/m² of residential space. In total (2007), the gas consumption of all 39 Volkswohnung buildings amounted to 9,040 MWhHo/a and the electricity consumption amounted to 2,159 MWhel. In comparison: Before the start of refurbishment in 1997, the gas consumption of these buildings was 10,500 MWhHo/a; after the 2nd refurbishment phase (as of 2009; 10 of 30 buildings have been refurbished) it is now 8,460 MWhHo/a.

If we compare the invoiced gas consumption of the 8 buildings which were refurbished between 1998 and 2000 with the gas consumption of the 10 identical but as yet unrefurbished buildings, we can estimate the consumption-reducing effect of refurbishment: The gas consumption was reduced by approx. 42 % relative to the consumption before refurbishment. In 2007 and 2008, the buildings in Forststr. 7 (point block, 9 stories) and Heilbronner Strasse 27-31 were comprehensively refurbished. The heating energy consumption here after refurbishment is 42 kWhth/m2 of residential space (measured) or 45 kWh/m2 of residential space (calculated). This is equivalent to a combined saving of 580 MWhHo or 58 % compared with the initial condition of these two buildings (approx. 1,000 MwhHo). Refurbishment of the 10 buildings to date reduced the gas consumption (heating, hot water) of all 30 buildings owned by Volkswohnung in the neighbourhood by approx. 20 % - compared with the initial consumption of all 30 buildings before 1998.

No gas invoices are available for four other residential buildings in the neighbourhood which do not belong to Volkswohnung. The following consumption data was estimated provisionally for these buildings: For the block of flats in Mannheimer Str. 27 – a 13-storey point block with 34 freehold apartments and 3,353 m² of residential space – an annual gas consumption of approx. 410 MWhHo/a and an electricity consumption of approx. 90 MWhel were calculated. For two other residential buildings (each with 34 accommodation units and a residential space of 5,200 m²) and an old people’s home (160 accommodation units with a residential space of 5,700 m²), the estimated gas consumption is 445 / 485 MWhHo/a, and the electricity consumption is 156 / 142 MWhel.

The Energy Management department of the City of Karlsruhe stated the following average consumption data for the period from 2005 to 2007 for the primary and technical secondary school south of Forststrasse (approx. 6,600 m2 of usable floor area). The gas consumption was 1,200 MWhHo/a (installed boiler capacity: 950 kWth) and the electricity consumption was 99 MWhel/a. The school is to be connected to the local heating network. At the same time, the building is also to be comprehensively refurbished, which should reduce the heating energy consumption by approximately half of this value. Refurbishment planning has not started yet.
After the implementation of the energy concept, which, in addition to building refurbishment also includes the installation of a local heating network, the primary energy factor of the heat supply is estimated to be approx. 0.445 MWhPE/MWhth (including heat losses in the transport network of 17 % and the pump power requirement of 4.1 % of the heat output): The district heating system of Karlsruhe municipal utility company is largely fed from industrial waste heat and cogeneration heat. If we assume that as a result of the as yet unplanned refurbishment program for the unrefurbished Volkswohnung buildings, the specific heat requirement of the buildings for heating and hot water decreases to an average of 75 kWh/m2, the heating requirement of the schools will be halved after refurbishment and the remaining buildings remain unchanged, the total heating requirement for the usable floor area of around 80,000 m2 in the neighbourhood decreases from 10,330 MWhth before the refurbishment measures (1997) to 5,830 MWhth/a after refurbishment (probably by 2015). The primary energy consumption decreases from 14,870 to approx. 2.600 MWhPE/a (around 33 kWhPE/m2), i.e. by over 80 %. The task of the project is to demonstrate the technical and economic feasibility of this decrease.

For two buildings pending immediate refurbishment (built in the 50s, with 30 accommodation units each), a feasibility study for the realisation of technical innovations was carried out as part of the research project in cooperation with RWTH Aachen. A range of different technologies from building physics, building services equipment and control technology are to be utilised to make one of the two buildings a "3-litre-house” after refurbishment. In the second building, more advanced innovations will be tested, including measures for passive and active cooling. Both buildings will be subject to ongoing monitoring and measurement by Karlsruhe University of Applied Sciences and RWTH Aachen.
The buildings to be connected to the local heating network in the future will be equipped with a data logger for ongoing system monitoring and system optimisation. In conjunction with the heat volume meters and heat cost allocators fitted with remote sensors in the apartments, regular energy balances can be drawn up right down to an individual apartment level. They will be made available to the tenants via a Volkswohnung customer portal, to give them incentives and information on energy savings. As a result of experience in an EnSan project, and another preliminary project, Volkswohnung expects this to result in potential heating energy savings of around 20 %. As electricity meter data (smart meters) is also to be recorded in cooperation with Karlsruhe Municipal Utility Company, the concept shall also attempt to influence the households’ electricity consumption.


50 % of the overall costs (€ 5.1 million) for the concept planning for the neighbourhood, the feasibility study for the two current building refurbishments, the innovative technical refurbishment of these buildings and the establishment of a monitoring system in the first expansion stage will subsidised as part of the EnEff:City research initiative. The realisation of the sustainability concept for the neighbourhood (until approximately 2015) will cost approximately € 35-40 million, which will be borne by Volkswohnung. Subsidy programmes – where available – will also be used.


The feasibility study for the innovative building refurbishment has been completed; detailed planning is currently underway with the involvement of manufacturers. The construction measures for the "3-litre building" started in July 2009 and the tender process for the experimental building was held in August/September 2009. The neighbourhood energy concept has now been completed. The data for evaluating the project will probably be available from autumn 2009. The measuring and monitoring project for the two demonstration buildings will begin from February 2010.

Energy characteristics

before potential after unit
Energy consumption area 81.600,00   85.600,00
Heating requirement (heating, domestic hot water) 127,00   72,00 kWhth/m²
Primary energy (heating, domestic hot water) 182,00   32,00 kWhPE/m²
Electricity consumption 32,00   30,00 kWhel/m²
Primary energy (electricity) 87,00   80,00 kWhPE/m²

Cost-effectiveness characteristics

before after unit
Investment local heating network   870,00 €/m
Pipeline length   2.600,00 m
Transportation costs 10,30 18,20 €/MWhth
Costs natural gas (2009)   63,00 €/MWhth
Costs local CHP heating (2009)   61,00 €/MWhth
Planning costs   4,00 Mio. €

Sustainability characteristics

before after unit
CO2 equivalents heating (according to GEMIS 4.5) 39,00 8,00 kg/m²
CO2 equivalents electricity (according to GEMIS 4.5) 59,00 55,00 kg/m²
  • BINE projektinfo publication "Integrated energy concept for a residential neighbourhood"