The world’s first Passive House building has increased its already high energy efficiency level and now relies on renewable energy.

About a year ago, a photovoltaic system was installed on the roof of a row house built in 1991 in Darmstadt. Since then, this pioneering Passive House project has been producing its own electricity, thus fulfilling the criteria of a Passive House Plus building. The official certificate was recently issued.

“Passive House buildings are perfectly equipped to utilise renewable energy. With their extremely low heating energy demand, it is even possible to derive as much energy from the sun on-site as is consumed in the house over a year”, explains Dr. Wolfgang Feist. Together with his wife Witta Ebel he recently accepted the Passive House Plus certificate.

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Photovoltaik system for the anniversary

Twenty-five years ago, building physicist Dr. Wolfgang Feist built the world’s first Passive House, thereby establishing this energy efficient construction Standard. Since that time, the founder and director of the Passive House Institute and his family have lived in the terraced housing complex in the Darmstadt city district of Kranichstein. In the year of its 25th anniversary, the Feist family installed a photovoltaic system on the roof of their house with a surface of 26 m² in order to utilise the sun’s energy.

Efficiency plus renewable energy

With the Passive House Plus Standard, Passive House has contributed to the second step of the energy revolution. In addition to being highly energy efficient, it also generates on-site renewable energy. What matters here is that the energy demand of a building is considered and optimised separately from the energy generation.

 Good basis for Passive House Plus

In a Passive House Plus building, the upper limit for the total demand for renewable primary energy is 45 kWh/(m²a). At the same time, at least 60 kWh/(m²ta) of renewable energy must be generated based on the projected building footprint. From the very beginning, the Feist family equipped their house, which has a living area of 156 m², with extremely efficient devices. The electricity consumption is therefore very low, even with the operation of the ventilation system.

 Heatpump with reduced energy use

The same also applies for the air-to-air heat pump that was recently installed for test purposes this past autumn, which is used for heating as well as ventilation in the Passive House. This electrically operated heat pump should use approximately 30 Percent of the energy consumption that was previously required with natural gas for the gas heating system.

Electricity surplus into the grid

In the summer the surplus electricity produced by the photovoltaic system in Darmstadt-Kranichstein is fed into the public grid. In theory, the produced amount would suffice for supplying the whole house for one year, and the surplus electricity in summer could be stored for the winter.

Saving in network is useful

“For a single household, this kind of seasonal storage is not a reasonable option, but in the network this “gap” becomes smaller and storage becomes much more cost-effective. This is what needs to be done in future”, explains Dr. Wolfgang Feist.