The German Ministry for Transport, Building and Urban Affairs contracted Fraunhofer-IBP in cooperation with the Federal Office for Building and Regional Planning and the company Megawatt to issue an energy certificate based on calculations with the standard DIN V 18599. The complex energy supply concept includes combined heat and power units based on biofuel, absorption cooling, seasonal heat and cold storages and connects via local district heating and cooling networks several parliamentary buildings. The building originally built in 1894 and retrofitted between 1991 and 1999 according to the architectural plans of Sir Norman Foster.

The work of issuing the EP certificate included the detailed analysis of the existing building including its building components, the installed building service systems based on architectural drawings and system schemes as well as building visits. The primary energy demand was calculated with the software tool ibp18588. The display of the energy performance certificate is presented as illustration to this case.

Though the total energy need of the building with 208 kWh/m²a is already rather low, the building especially profits from the heating and cooling generation by renewable energy or more specific biofuel. 

For the calculation according to DIN V 18599 the building was distinguished into 15 thermal conditioned zones and two additional unconditioned zones. A scheme presenting the zones of the 1st floor is presented below. The zone reach from offices to meeting rooms, traffic areas, common rooms, technical rooms, server rooms, kitches, canteens to the plenary chamber and restaurants, many of them available also as cooled zone.

The total net floor area of the Reichstag building amounts to 40047 m².

The U-values range from 0.15 W/m²K to 0.89 W/m²K for the opaque building components and from 1.8 to 2.0 W/m²K for windows, glazed roofs and doors. With a total surface area of 65903 m² the average transmission loss coefficient was calculated to 0.51 W/m²K thus being less than one third of the maximum allowed value for new buildings of 1.62 W/m²K.

The primary energy demand for all energy uses (heating, hot water, lighting, ventilation and cooling) was calculated to 270.9 kWh/m²a, while the maximum allowed primary energy demand for this building if built in 2009 would be 446.1 kWh/m²a and the reference value for a correspondent existing building is 624.6 kWh/m²a. These values show that the Reichstag building is a very good show case for public buildings as leading examples.

The calculated CO2 emissions of the building amount to 24.9 kg/m²a.