Case Study: Heidelberg-Bahnstadt

Heidelberg-Bahnstadt in Germany is a new mixed-use district located just 60km south of the first ever Passivhaus construction in Darmstadt. The district covers 116 hectares and will house approximately 6,500 people, all of whom will have a healthy home, which will be affordable to run chiefly thanks to the Passivhaus standard being adopted as a universal construction method.

Ralf Bermich is responsible for the climate protection programme and the municipal energy management of the City of Heidelberg. I saw him speak at the Passivhaus conference and met with him to find out more about how Heidelberg-Bahnstadt was built to the Passivhaus standard.


Bermich highlighted four key ways to enforce Passivhaus on new developments:

  1. Require city-owned buildings to be built to the Passivhaus standard.
  2. Make Passivhaus a requirement in the private sale of city-owned plots.
  3. Integrate Passivhaus into planning policy.
  4. Make Passivhaus the requirement for a whole district, like Heidelberg-Bahnstadt.


The construction contract was made between the city and the development company. Together they set the goals of the development. By writing ‘Passivhaus’ into the contract investors are required, as an instrument of private law, to fulfil the energy concept.

Quality assurance

The development was divided into a number of sub-plots which were awarded to different Contractors. Each Contractor was responsible for ensuring the buildings were built to the Passivhaus standard by engaging an energy agency to carry out quality assurance procedures. They check the PHPP models, thermal bridges, airtightness and ventilation. The aim was to get as close as possible to the Passivhaus Certification process.


The City of Heidelberg has in place three motivational instruments that help realise Passivhaus projects and advance their public profile:

  1. Energy subsidy programme: €50/m² of Passivhaus (up to €5,000 per unit)
  2. Education (partly city-financed): Series of Passivhaus seminars for architects and engineers.
  3. Public relations: Press information on realised projects.

The build cost of Heidelberg-Bahnstadt is in the same region as non-Passivhaus projects of a comparable scale. However, the energy costs required to run the homes are significantly lower.

This development demonstrates that money is not the real reason for resistance to sustainable design solutions. It is pushed to the forefront and misrepresented so that stakeholders can avoid deviating from ‘the norm’. Pioneering projects, like Heidelberg-Bahnstadt, will make the financial arguments to avoid Passivhaus increasingly spurious.

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