RheinEnergie AG, Cologne: sustainable and efficient spaces for the energetic.


This elegantly contoured building blends harmoniously into Cologne’s Parkgürtel district. Its well-conceived, energy saving building services make it one of the most environmentally friendly administrative buildings in all of Germany.


RheinEnergie AG is constructing a new administrative centre at its business campus in Cologne’s Parkgürtel quarter. The harmoniously contoured design of the new building stands for energy flow and vitality – qualities also reflected in the concept for flexibility and adaptable interior design. The building is to be planned and constructed in such a way that it fulfils the highest ecological demands both initially and throughout its entire lifecycle.

With its challenging building concept based on the use of state-of-the-art, energy saving technologies and the use of renewable energies, RheinEnergie AG is setting a clear example as an environmentally friendly and ecologically oriented company. Principles of sustainable building are to be applied throughout, beginning with the initial selection and use of recyclable, environmentally friendly materials produced using energy efficient methods.

The new building is to offer space for about 2,000 employees, a customer centre, meeting and conference rooms, a company cafeteria as well as a childcare facility and a fitness area. Despite its large size, nearly 57,700 square meters of floor space, the building requires very little energy for its day to day operations. State-of-the-art technologies ensure that energy is used as sparingly and efficiently as possible. The new building’s energy consumption is not to exceed the specific total primary energy threshold levels of 100 kWh/m² annually as prescribed by the German Energy Saving Ordinance (EnEV 2009).

Project description

The vast majority, about 90 percent, of the required heating supply is generated by a heat-pump system using geothermal energy. Another 5 percent is provided by RheinEnergie AG’s heating grid with the remaining five percent coming from a dedicated solar heating system. 75 percent of the building’s heat is recovered and reused by its advanced ventilation systems.

Energy saving heating panels installed in the ceilings create a comfortable indoor environment. The system operates at an extremely low temperature between 29 and 35 degrees Celsius. The heating panels are equipped with electro-thermally controlled regulator valves in order to further reduce energy use. Ventilation and air conditioning systems in line with the latest energy efficiency and comfort standards are used throughout the building. Additional energy savings are achieved using a heat recovery system as well as adiabatic cooling of the outside air in the summer months.

A well system utilizing geothermal energy provides for up to around 60 percent of cooling requirements. Another 20 percent is covered by adiabatic ambient air cooling systems and water-cooled chillers. In the winter months, another five percent is provided by cooling towers. Cooling panels installed in the ceilings provide energy-saving air conditioning. This allows the system temperatures of the chilled water distribution system to be set very high at 16 to 19 degrees Celsius which, in turn, achieves especially high annual performance coefficients. A solar heating system provides about 50 percent of the energy required for the warming of drinking water and a rainwater utilisation system reduces the amount of fresh water required to maintain the property’s lawns and grounds.

A RheinEnergie AG 10-kV-medium voltage power grid is to be used for the power supply. Individual monitoring of energy use by the lighting systems in specific areas of the building is made possible by equipping the electrical sub-distributors with internal digital meters connected to central controls via bus line. Work stations are to be equipped with modern, efficient lighting systems using LEDs and other advanced technologies. The lift systems are also equipped to save energy; they use innovative technology to recycle and feed surplus energy generated by empty or descending elevators back into the building’s internal power supply. This can create savings of up to 75 percent in comparison to conventional elevator systems.

All buildings will be equipped with a master energy-management system. This master system is connected directly to all of the building’s services as well as metering and measurement devices and service disruption detectors. An automated energy consumption monitoring system is to be installed so that annual threshold values required for DGNB (German Sustainable Building Council) certification may be documented appropriately.

Special Feature

Maximized CO2 reduction using renewable energy sources.

The new RheinEnergie AG administrative building sets itself apart from comparable properties most clearly in its comprehensive use of renewable energy sources for the powering of heating and cooling systems. This significantly reduces the consumption of energy and natural gas, thereby also greatly reducing the emission of CO2 gasses. 95% of the heating energy and 85% of the cooling energy required in the main building comes from environmentally and climate friendly sources. At the core of the “green building” concept is one of Germany’s largest geothermal power systems. The system, equipped with six extraction and injection wells, draws from renewable energy sources to cover the majority of the administration building’s energy requirements. The Cologne energy utility’s new administration building sets true benchmarks in terms of sustainable and environmentally friendly operation.

Project Facts:

Initial Planning: 2008

1st construction phase: 2015
2nd construction phase: 2018

Building Services Construction Costs:
approx. 50 M euros

Plumbing: solar heating systems heat up to 50% of the drinking water.

Heating: approx. 90% via geothermal heating, approx. 5% from the RheinEnergie AG heating grid and approx. 5% from solar thermal energy. Use of ceiling heating panels with very low system temperatures.

Ventilation: ventilation and air conditioning systems of the highest efficiency class with temperature and CO2 regulation, 75% heat recovery in the ventilation systems.

Electric: lighting system implementing ballast units. Use of LED lighting.

Cooling: approx. 60% via geothermal cooling (well system), approx. 20% via adiabatic cooling of ambient air and approx. 20% via high-efficiency cooling units.

Conveyor Systems: regenerative electrical motors return surplus energy into the building’s internal power grid.

Building Automation: master energy-management system of the highest efficiency class for the automated regulation, control, centralized management and monitoring of all operational systems.