Fraunhofer Institute for Building Physics IBP
Fraunhofer Institute for Building Physics IBP

EnEff:Stadt: Collaborative project “Herzo Opt” - monitoring plus-energy houses with shared energy systems and optimizing their operation

Subproject: Evaluation of long-term monitoring and accompanying research

Terraced housing complex in the “Herzo Opt” project
© Technischen Hochschule Nürnberg
View of the terraced housing complex in the “Herzo Opt” project.

Herzo Opt is a terraced housing complex that was planned and put into operation in a previous project called “Herzo Base - an energy-flexible building and energy concept of tomorrow” by the Nuremberg university of applied sciences Georg Simon Ohm. Extensive sensor technology had already been integrated for subsequent close monitoring. In the Herzo Opt joint project, energy monitoring with operational optimization of a terraced housing complex was transferred to a long-term monitoring program and scientifically accompanied by scientists from the Fraunhofer Institute for Building Physics IBP for a period of three years.  

Project goals

The aim of the collaborative project was to scientifically study the terraced housing complex over a period of three years and to continue optimizing its operation. The complex is made up of eight houses that were completed in December 2017, and all occupied by March 2018. The houses are supplied by a shared system of geothermal probes, heat pumps and PV system including battery storage. To monitor a lighthouse project over a long period of time and to develop control strategies for a terraced housing complex, different disciplines were combined and networked.

Nuremberg Tech was responsible for optimizing the operation of the various systems. Measurement data were saved on the on-site database every 15 minutes and then imported to IBP's own database and validated. The following variables were evaluated at Fraunhofer IBP on a monthly basis:

  • Weather conditions
  • Energy consumption
  • Cumulative energy (consumption - yield)
  • Percentage of own energy consumed
  • Degree of self-sufficiency
  • Battery utilization rate
  • Heat pump performance figures (different balance limits)

Project results

Over the course of the 3-year project, monitoring showed that the plus-energy standard was achieved each year.

The electricity yield from the PV system ranged from 140 to 163 percent of the housing complex's total electricity consumption during the project.

The consumption of energy from the PV system by the complex is derived from the direct consumption (27 to 30 percent) and battery charging (13 percent) and lay between 40 and 43 percent.

The degree of self-sufficiency during the project period was between 60 and 65 percent.

Project partners

Technische Hochschule Nürnberg Georg Simon Ohm

  • Faculty of Mechanical Engineering and Supply Engineering
  • Faculty of Electrical Power Engineering
  • Faculty of Materials Engineering
System diagram in project "Herzo Opt"
© Technischen Hochschule Nürnberg
System diagram (incl. heat meters).
Cumulated energy consumption and energy yield
© Fraunhofer IBP
Cumulated energy consumption and energy yield (example 2021).
Electrical energy consumption and PV generation
© Fraunhofer IBP
Electrical energy consumption and PV generation (monthly, example 2021).