Research Project: Standard climate versus local climate - Investigation of the future usability of local climatic boundary conditions derived from the new local test reference years for energy verification

Project briefing

• Status Completed
• Project duration September 2018 – June 2020
• Programme Future Building

In energy requirement calculations for public law verification, the climatic boundary conditions of the Potsdam site have so far been used uniformly for the whole of Germany. By using local climate data, the difference between calculated demand and measured consumption could be reduced and beyond that more economical building constructions could be possible.

Background

According to the requirements of the EnEV (Energy Saving Ordinance for buildings in Germany) for energy demand calculations, a defined reference climate must be used as a basis for climate data and not climate data of the building’s location. The use of a reference climate for the EnEV verification requires the minimum insulation standard of a building resulting from the requirements specifications to be determined independently of the actual prevailing climatic conditions.

If the use of local climate data for energy demand calculation were permitted, improvement measures could be compared more accurately and one cause of the frequently large deviation between calculated demand and measured consumption could be eliminated.

Thanks to the BBSR-sponsored project "Local German Test Reference Years”, hourly climate data is available for every location in Germany since 2017; it can be downloaded free of charge from the "Klimaberatungsmodul" website of the German Meteorological Service (DWD). This has now created the basis for calculating energy requirements using the local climate data of the building location. However, in the EnEV calculation the climate data for outside air temperature and solar radiation is not included as hourly values , but as monthly average values. Furthermore, it is also difficult to assess the effects of a calculation with local climate data on the primary energy requirement value.

Objective

The usability of local test reference years for energy verification was investigated within the framework of this research project. For this purpose, the hourly values of the local test reference years had to be converted into monthly mean values, which is a basic requirement for carrying out the energy demand calculations with local climate data in accordance with DIN V 18599. The effects on selected residential and non-residential buildings were examined on this basis, using different constructional and system engineering concepts.

Contractor of the project was Ingenieurbüro Hausladen GmbH, Kirchheim.