Projektinfo – Detailed information on energy research

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The mirror-image building halves after refurbishment, left building half: standard building – refurbished according to Hamburg's climate protection programme, right building half: EnSan building
Two energy standards being compared
Projektinfo 08/2008

Fig. 1: The mirror-image building halves before refurbishment.
© Dittert & Reumschüssel
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Building refurbishment – Gründerzeit houses

Today, residential buildings from the Gründerzeit are still characterise entire streets, or even districts. These Gründerzeit houses, built between the turn of the century and 1918, are the most characteristic of old inner-city buildings. In many cases, these quarters are now among the most preferred residential locations. Spacious layouts, high ceilings, and the elaborate stucco with which the houses are decorated make them particularly sought-after. This was not always the case. It was once common practice to tear down the Gründerzeit architecture, and to replace it with new buildings. Only in the 1970s could the demolition be stopped, and careful refurbishment of the remaining building fabric began. Today, many of the buildings are protected as listed buildings.

Perimeter block developments of around four to six storeys with richly decorated facades are typical of the Gründerzeit architecture. On the courtyard side, the facade is usually undecorated. Exterior masonry walls which taper from the ground storey to the storeys above are typical. Wooden beam ceilings are found in the upper storeys, and usually steel girder ceilings above the cellar. In some cases, there are bathrooms situated in the flats. The buildings were originally heated by individual stoves. It is not unusual for the heating requirement to be around 300 kWh/m² p.a.
In Hamburg, the energy-oriented refurbishment of this building standard has been implemented by way of example, with a Gründerzeit house which consists of two structurally identical building sections. The objective was to realise different refurbishment concepts, so as to compare them in terms of efficiency and costs.


The refurbishment occurred according to two standards: one half of the house according to the Hamburg climate protection programme, and the other according to the stipulations of the research field "Enhanced building fabric performance" (EnSan), which is part of the support initiative "Energy-optimised construction" (EnOB). One goal of the refurbishment was to reduce the calculated primary energy consumption of approximately 315 kWh/m² p.a. by more than 50%. In this research project, sponsored by the German Federal Ministry of Economics and Technology, special attention was paid to the development of transferable solutions for the refurbishment of Gründerzeit houses. For instance, interior insulation of the front facade and new refurbishment solutions for balconies and beam heads were called for, in order to reduce heat losses and to prevent moisture damage. The work has now been completed. The building is occupied once again, and has been subjected to intensive testing on the basis of measurements.

Projektinfo 08/2008:
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Project management
STEG Hamburg mbH

Building services equipment
innovaTec Energiesysteme GmbH

Measurement technique
TU Hamburg-Harburg, ABT

Quality assurance
Passivhaus Institut

Documentation and public relation
target GmbH