e4 single-family house in Germany

SFH in Freiberg, Germany

A self-sufficient house

What does a house look like, which is energetically self-sufficient? In what way does it have to be conceived to do without a connection to the public power supply system? In Freiberg, two single-family houses were built to find out exactly that.

Completely independent

The special characteristic of this research project: both single-family homes are in fact energy self-sufficient and do not require a connection to the public power grid – fully in accordance with the e4 brick house concept by Wienerberger. The entire electricity and heating demand is covered by the sun. This is made possible through the combination of solar thermal energy and photovoltaics as well as an additional bio-mass heating system if necessary.

Brick and sun – a profitable alliance

Since this construction and heating concepts is based on a heat source, which is available for free and in any required quantity, brick masonry is an optimal addition. Owing to their high, natural storage capacity, monolithic walls built of clay blocks balance variations in temperature and provide excellent thermal insulation without an additional artificial insulation layer. Therefore only high-quality clay blocks, bricks and clay roof tiles by Wienerberger were used for the entire building envelope as well as for interior walls, ceilings and the roof.

Perfectly coordinated

The aim to solely provide a single-family house with renewable energies requires more than just the perfect coordination of building services. Each building is equipped with a solar thermal heating system. Collectors integrated in the roof area collect solar heat. A 9.3 m³ high-capacity long-term heat storage, the technical centrepiece of each house, absorbs the heat and gives it off to the rooms by means of underfloor heating. On especially cold winter days, a wood gasification plant with a water compartment serving as heat exchanger additionally feeds the storage.

Equipped with its own power plant

The 58-square metre photovoltaic system installed on the roof generates electricity for lighting and household appliances. To ensure that this electricity is available independent of solar radiation, the generated power is buffered in a multi-cell electric energy storage with a capacity of 58 kilowatt hours. A special measurement, control and regulating system is responsible for the efficient use of energy. The own consumption respectively storage of the electricity generated on the rooftop pays off for the residents in two respects: they need not buy power from the mains at a high price nor do they have to pay tax on revenues from feed-in compensation. Furthermore, the clients can make use of electric mobility. So the solar yield is not reduced at all; expenditures for the plant are paid off even sooner and the residents are independent of fluctuations in prices and compensations.

Key Data

Living area:
161,41 m²
Primary energy consumption:
6,81 kWh/m²a
Thermal heat consumption: 41,40 kWh/m²a
Construction costs: 2.465 €/m²
Masonry: Monolithic masonry with integrated insulation
Exterior walls: 42.5 cm Poroton-T8-P filled with Perlit
Interior walls: 7.5 and 24.0 cm clay block Plan-T 12-0.9
Building services & heating technology
46 m² thermal solar system
8.4 kWp (58 m²) photovoltaic system
9.3 m³ long-term heat storage
25 kW wood gasification plant with heat exchanger
Central ventilation system with heat recovery

Project information

Project: The energy self-sufficient house by HELMA in Freiberg, Germany
Planning – building: HELMA Eigenheimbau AG
Planning – building systems:
TU Bergakademie Freiberg
Wienerberger AG
DRECHSLER Haustechnik GmbH
Jenni Energietechnik AG
Buschbeck Energiesysteme GmbH
Fa. Timo Leukefeld

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