System monitoring ensures energy-saving heat generation in the Artem residential district
The apartments in the new Artem district in Oberursel are supplied with heat by Conergia Energieeffizienz GmbH on a contracting basis. Air-to-water heat pumps supply the heating energy and the higher temperature for hot water is generated by eXergy machines. They handle the reheating with a COP of around 5 and reduce the load on the heat pumps. Thanks to monitoring, Conergia always has an eye on the heating systems and their efficiency. A system that pays off - for the heating customers and the contractor.
The „Artem“ quarter developed by WILMA Wohnen Süd RM GmbH in Oberursel (Taunus) offers 67 residential units in six buildings on a city site. The houses comply with energy efficiency class EE 55, i.e. they use at least 55 % of renewable energy. Important components of the building technology include air-to-water heat pumps, energy-efficient heating and hot water technology and photovoltaic (PV) systems. Each building has its own PV and heating system.
Sustainably supplied through heat contracting
Conergia Energieeffizienz GmbH, based in Bad Vilbel, operates the heating systems on a contracting basis. Conergia project engineer Ralf Kaiser explains the advantages: „Contracting allows the property developer WILMA to concentrate on its core business and the residents or apartment owners have an experienced partner for their heat supply.“
Electric reheating with a COP of 5
As the heating load of the new buildings is low, the energy requirement for water heating is more significant. The contractor has therefore implemented a concept that enables hygienic hot water preparation in a second stage with low energy consumption. The heating technology is divided into a low and a high temperature range. The respective air-to-water heating heat pump supplies around 40 °C in the flow and charges a low-temperature storage tank to which the heating circuits are connected. The higher temperature for hot water preparation is provided by the eXergy machine (eXm). This is a special water-to-water heat pump developed by the partner companies varmeco (Kaufbeuren, Germany) and BMS-Energietechnik (Wilderswil, Switzerland) for high source temperatures of up to around 55 °C.
The eXergy machine uses the energy in the low-temperature storage tank as a source, raises the temperature to approx. 65 °C and charges a high-temperature storage tank, which supplies the water heater(s) with heating energy. A wall-mounted eXm with a maximum thermal output of 5 kW was installed in each of the smaller buildings, each with a maximum of eight residential units, and a free-standing unit with a maximum of 20 kW was installed in the larger building with 28 residential units.
Efficient reheating reduces the power requirement of heating technology
As the eXergy machine manages the temperature range from 40 to 65 °C with a high COP of around 5, hot water preparation is very energy efficient. The heating heat pump can work in its ideal operating range and achieves a high seasonal performance factor. Kaiser comments: „Although we install additional electrical consumers with the eXergy machines, the overall efficiency of the heating technology increases significantly.“
Monitoring of system operation
System monitoring is important for heat supplier Conergia Energieeffizienz GmbH, says the project engineer: „We monitor the heating technology via a browser application.“ The operating data of all heat pumps, eXergy machines and water heaters can be viewed on a PC or tablet. With varmeco technology, a VarCon380 system controller connects the varmeco devices of all buildings in the Artem via a data bus and provides the data for the browser application. „This allows us to evaluate the data and optimize the system settings. This ensures high energy efficiency. This is another advantage of contracting. With an owner-operated system, nobody usually looks closely at the operating data after commissioning, but we always have an eye on efficiency. This conserves resources and ensures low heating costs.“
