Until 2014, the apartments in this multi-family building located in the Hamburg suburb of Bergedorf were heated using electrical water heaters and supplied with domestic hot water using electrical instantaneous water heaters. Now, after the renovation, a block heating station in the basement of the building provides heating distributed via flat stations installed in the stairwell and used for decentralized domestic hot water. Tenants were able to stay in their apartments throughout the renovation process.
Decentralized supply pays off:
When renovating existing building stock, the focus is often on upfront investment costs, even though these only make up for a small part of the total life-cycle costs. It is true that the upfront investment in a conventional centrally located boiler system is around 15% lower than a system installed in combination with flat stations, yet lower heat losses and lower heating costs make for a rapid return on investment. In addition, a heating system using flat stations only requires three supply lines (heating supply, return and cold water) instead of the usual five. Because the drinking water is heated decentrally in each apartment, separate pipes for hot water supply and circulation can be eliminated.
Renovation highly needed:
Three quarters of all apartment buildings in Germany were built before 1979, i.e. before the first Heat Insulation Ordinance came into force. This unrenovated stock of older housing is responsible for 95 percent of energy consumption in buildings, Fraunhofer researchers estimate. It is possible to renovate this old building stock and bring it up to the state-of-the-art, as this example shows.
Renovation while residents remain in their apartments:
Whereas all the tenants whose apartments are located in the same vertical segment of the building need to be present at the same time when renovating systems relying on centralized heat distribution via vertical pipes for heating and domestic hot water, the process involved in the decentralized flat station solution is considerably simpler. In this project, there was enough space in the stairwell to install risers and flat stations without inconvenience for the tenants. Only when laying the horizontal connections from the stairwell to the radiators and taps in the kitchens and bathrooms the tenants’ presence was required. If the tenant could not be reached at home during the final phase of the project, the installation team was able to move on to another apartment instead.
Flat stations:
EvoFlat flat stations are available for surface or recess mounting as a standard feature, with fittings for optional energy meters and water meters. This makes it possible to verify, record and bill for consumption at any time. An integrated fresh water system with a MicroPlate heat exchanger ensures hygienically safe decentralized domestic hot water heating. The TPC-M controller is a key component. In a single component, it combines the functions of a differential pressure and flow controller, zone valve, thermostat and de-aerator. This way, it provides instantaneous DHW heating with a high degree of temperature stability, low return temperatures and reliable, energy-efficient operation, even with primary-side pressure and temperature fluctuations. Thanks to the internal ClickFit pipe connections, the EvoFlat flat stations do not require the usual time consuming tightening of threaded joints.