The "Nulli" in Dörpe


The "Zero-energy house" in Dörpe near Hannover.

The "zero-energy house" by Erhard Wiers-Keiser and the organisation for "Ecological Future Workshop for Minimum-energy and Zero-energy Houses e.V." (1989) was calculated as having smaller demand values than a Passive House, but unfortunately the consumption values during operation were higher. Problems were due to reduced airtightness (non-reinforced building board), the insulation shutters on the inside and the solar storage technology. The annual 10 m³ solar storage was later removed to make space for a new wing, but the house was still used as an "almost Passive House" as before. Robert Borsch Laaks contributed significantly to the details.

Many members of the Passive House Research Group were involved in this project.