The Flintenbreite neighbourhood is a market-driven project emphasizing innovative infrastructure services for energy efficiency. In 1999, a portion of the dwellings (for 111 inhabitants) and a technical building with a community center were constructed. Notable elements in Flintenbreite are separation of blackwater, greywater, and stormwater; vacuum sewer and anaerobic digestion of organic refuse; and a local integrated infrastructure provider company. The local infrastructure company provides electricity, heat, water and wastewater service from one technical building. The technical building is the hub of infrastructure provision. The service machines are hidden in the basement and in the back of the ground level. The rest of the ground level is the community center, consisting of a large room, an alcove with a kitchenette, an outdoor patio, and bathrooms.
- ->100 kWh/year electricity
- ->120 MJ/year sun energy
- ->120 m3/year drinking water
- ->120 m3/year food
- ->120 m3/year oxygen
- 280 m3/year purified water->
- 280 kg/year CO2->
- 280 kg/year liquid effluent->
Description of the Process
Households are supplied with warmth from natural gas CHP housed in the technical building through a local heat network. The heat network makes a ring through the neighbourhood. At each block, the local heat network passes through a heat exchanger to warm drinking water for household use and space warming. The technical building is also an intermediary between the national electricity and gas grid and the households. All water consumed is drinking water from the municipality in Lubeck. Greywater is collected in the households and brought to a constructed wetland by free-flow pipes. The constructed wetlands are vertical-flow type built at 2 m2 per person. The effluent is cleaner than that of the municipal WWTP. Blackwater is collected by the vacuum sewer into the technical building. Separated refuse and mixed refuse are handled in the manner conventional to Lubeck; namely by curb side bins collected weekly by trash truck. Organic refuse is collected within the neighbourhood in a separate container and can be manually added to the anaerobic digestion process to produce additional energy. The infrastructure is supplied to the rows of dwellings in a neat package that sits about 1.5 meters by 0.3 meters, including the hot water, hot water return, vacuum sewer (63 mm pipe diameter), drinking water, electricity, and telecom. In the more recently built rows, access to the infrastructure bundle was improved for inspection and maintenance.
Flintenbreite was built a greenfield site in the suburbs of Lubeck as a housing area for families.
The investment for neighbourhood infrastructure and the technical building with a community space was made by the integrated infrastructure provider, the independent company Infranova GmbH & Co KG. The building construction was done by one developer (Schutt) and the vacuum system was built by Roediger Vacuum GmbH, who also supplied the vacuum toilets. The neighbourhood was built without any government subsidies, expect for a planning subsidy given to OtterWasser GmbH for designing the separated water system. The homes are available at market price, and may even be slightly lower than market price, given the amount of green space surrounding and location adjacent to a primary school.
Result of project
Impressively, Infranova GmbH is able to provide service for 20% less than conventional suppliers. This is attributed to the integration of the infrastructure provision. The economic success as well as the ecological success of the project is a positive case study for other decentralized neighbourhood infrastructure projects.
Problems during the the realization of the project and how they were approached
Minor problems have occurred with the vacuum sewer. In the first two months there was an adjustment period for inhabitants’ behavior. After this period, errors continued to be caused by clogging of the vacuum valve by inappropriate refuse in the toilet. OtterWasser has suggested that this problem could be solved by repetition of information to the inhabitants. Long-term build up from the precipitation of struvite and carbonate in the pipes has also needed to be solved by treatment with hydrochloric acid once in five years. The toilets installed are still functioning well, but are considered too noisy. However, since installation eleven years ago, Roediger has improved their technology to make quieter toilets. The constructed wetlands for greywater purification are performing exceedingly well, even after so many years and even in the winter. Due to the warmth of the greywater, there has been no freezing in the settling tank or in the wetland itself. The other decentralized infrastructure, including the gas CHP, hot water network, storm water infiltration, and community center have performed without any noted difficulties. Socially, there has been a positive response to the development, including pride over the infrastructure and adaptive use of the community center.
Role of different stakeholders in the system during the realization and maintenance of the project
Infranova GmbH employs one full-time caretaker who had previous experience as a hotel caretaker, so he is familiar with HVAC systems. The owner of Infranova is Ralph Otterpohl, whose company OtterWasser conceptualized the neighbourhood. The inhabitants can be stakeholders in Infranova for a one-time fee of €350.00. As stakeholders, they have a vote on community issues but do not share any profits. In fact, Infranova is not run as a profit business; it simply keeps the cost of infrastructure services as low as possible. The residents profit from the more intimate relationship with their infrastructure provider. OtterWasser is called upon 2-3 times a week for conversations about the neighbourhood regarding issues not related to infrastructure, such as gardening tips. Generally, inhabitants are proud of their neighbourhood and the infrastructure.
Contribution of the project to the design practice
Flintenbreite is a successful case decentralized infrastructure services, notably including the vacuum sewer, which is viewed with skepticism by many. Infranova GmbH further shows the management of decentralized infrastructure can be economically sustainable and with a simple organizational structure. The practical data generated in its first eight years of operation gives an indication of what can be expected if a similar system is applied. For example, the amount of blackwater in a vacuum sewer (6 liters/ capita per day), concentration of nutrients in the wastewater, the energy used in operating the vacuum sewer (45 kWh/capita per year), and the socio-technical operation of a combined community center and technical building.