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Housing estate modules for existing residential districts – impetus for linking energy efficient technologies

EnEff:Stadt - Forschung für die energieeffiziente Stadt
SWIVT project: Aerial view of the Postsiedlung housing estate in Darmstadt’s Bessungen district.

Aerial view of the Postsiedlung housing estate in Darmstadt’s Bessungen district.

© TU Darmstadt

Settlement summary

Block, ensemble
Project status Projektstatus: Phase 1Concept
Location of local community Postsiedlung, 64295 Darmstadt, Darmstadt, Hessen
Settlement in figures 122.11 km²; 150,000 inhabitants
Developer, organizer TU Darmstadt, Universität Stuttgart, AKASOL GmbH
Settlement 1950s housing estate, un-refurbished, medium-density linear apartment blocks close to the city centre.
Utilisation type Purely residential
Gross floor area, before 8.056 m²
Living area, before 8.056 m²
No. of residential units, before 79
SOI (Site Occupancy Index) 0.16
FSI (Floor Space Index) 0.77
Age structure Built between 1949 and 1957 (5 buildings)
State of construction and refurbishment Poor – requires considerable refurbishment
Heating system Building-based central heating (natural gas),3 x individual gas-fired central heating systems (natural gas)
Ownership structure Renting through municipal building society
Project themes

Project description

Buildings and their energy management are currently largely considered on an individual basis. Energy-plus houses are also mostly designed on an individual basis. Although they provide surplus energy in the annual balance, they make use of the public grids as a buffer, and can therefore contribute to their overloading. Energy-plus housing estates, on the other hand, attempt to ensure the energy balance throughout a group of buildings. However, so far they have been realised exclusively in selected development areas so as to minimise disruptive variables. The cumulative consideration of the generation and consumption of electrical energy creates aggregation effects that smooth out the overall consumption. This enables the stochastic proportion of the consumption to be reduced. This facilitates decentralised provision and at the same time reduces the transport losses and the need for compensation mechanisms at higher network levels. Bundling technologies at the housing estate level (for example, CHP plant, storage systems) creates additional benefits in terms of the investment and operating costs.

Systems with different characteristics are required to generate and store the energy. In order to minimise the costs, different energy technologies can be combined to form hybrid systems and constellations.

Communal climate protection concept and solar land register

In cooperation with the AEROWEST and simuSOLAR companies, the "City of Science " Darmstadt has produced an extensive land register of the solar potential with the aim of promoting renewable energy and strengthening the local economy.

The municipal climate protection concept serves as the programmatic framework and guideline for implementing climate protection projects in Darmstadt. Its principles were developed in a year-long process involving citizens and institutions from industry and commerce, mobility providers, energy suppliers, scientific institutions, housing associations and environmental organisations. The project is managed by Darmstadt’s Environmental Agency. The climate protection concept was created by the Institut für Wohnen und Umwelt in collaboration with the Memo-Consulting engineering office.

The Darmstadt Postsiedlung housing estate - Status quo and planning

The basic two- to three-storey residential buildings in the Postsiedlung housing estate in the Darmstadt district of Bessungen were constructed in 1949 by a housing association in order to create workers' dwellings. In order to increase the volume and density of the residential space, several rows of 1950s buildings outside the project’s section of the housing estate have already been increased in height by two storeys in recent years. Although the other buildings have not yet been renovated, there are also plans to refurbish them. To apply the "energy active" housing estate module, a smaller, two-storey building has been selected, which is planned to be fully renovated. The energy consumption (final energy) of the existing residential buildings corresponds to the un-renovated building standard of the period when they were constructed. They currently lie 3 to 4 times higher than current energy efficiency standards.

Project programme

In the SWIVT research project, housing estate modules are being configured and refurbishment strategies and concepts developed at the district level. The research will focus on the following areas:

  1. Utilising technological innovations.
  2. Linking different areas and players.
  3. Developing modern methods for the monitoring and energy management.

As part of the research project, four existing buildings are being refurbished and linked together using a newly developed "energy-plus module" (heat and electricity produced using PV, solar thermal and possibly CHP). The aim is to increase the residential space. The project can be divided into three phases. Based on a high-resolution, energy-related analysis of the existing housing estate, the first phase will be concerned with developing an energy-positive module in conjunction with the developer Bauverein AG, the energy provider HSE AG and specialists for innovative energy components. Based on the determined load profiles, the second phase will involve the development of energy generation and storage systems at the component level in conjunction with AKASOL GmbH, the construction of prototypes and the design of a master control logic. The third phase includes the trial operation of the individual components as well as the validation of the control system using the linked subsystems. An ecological and economic evaluation of the systems will also be conducted in parallel.

Energy characteristics

before potential after unit
Usable floor area 7.893,00    
Final energy requirements (electricity) 50,20     kWh/m²
Final energy requirements (heat) 238,10     kWh/m²
Primary energy requirement (electricity) 261,90     kWh/m²
Primary energy requirement (heat) 120,49     kWh/m²