Efficiency House Plus – A Concept in Practical testing (5-067-15)

Antje Bergmann, Fraunhofer Institute for Building Physics, Germany
Hans Erhorn, Fraunhofer IBP, Germany

This is a peer-reviewed paper.


building envelope, best practice, energy demand, primary energy, renewable energy, measurement and evaluation, Efficiency House Plus, electro-mobility


In the context of the promotional programme “Pilot projects achieving Efficiency House Plus Standard“, established by the former German Federal Ministry BMVBS (now adopted by the German Federal Ministry BMUB) 32 projects are supported. At present, 25 houses have been completed and are now undergoing a monitoring programme.

In the annual balance, a so-called 'Efficiency House Plus' generates more energy than it needs for its own use. It either feeds surplus energy back into the public grid or uses it for electro-mobility. To assess the energy demand an extended analysis according to the German EnEV (Energy Saving Ordinance) is required. This calculation method includes the required energy demand for lighting and domestic processes from 20 kWh/m² to a maximum of 2500 kWh/a per housing unit. The Efficiency House Plus standard is achieved if a building has both a negative annual primary and a negative annual final energy demand.

Most buildings have a compact design and the energy performance of the building constructions is opti-mized. As a rule, the heating demand of most of the pilot houses is slightly above the energy requirement of passive houses. The optimization of both building construction and technical equipment led to the best possible economic concept. To cover the required heat demand, heat pumps with different heat sources are used in most houses. All buildings are equipped with a mechanical ventilation system using heat recovery. Energy profits are gained by photovoltaic modules installed as roof-top or roof- or façade-integrated solutions. To increase the degree of self-use, surplus energy is stored in a battery in some of the houses. The installed capacity of the photovoltaic systems is between 8.5 kWp and 24.5 kWp.

In the scope of a monitoring programme, the energy flows of the buildings are measured, recorded, and analyzed by Fraunhofer IBP. The measuring configuration intends to determine both the monthly energy balances of the building and the performance of the installed technology. Until now, after a 12-month measurement period, only 2 of the 17 buildings measured failed to achieve the efficiency house plus standard.

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Panels of the eceee 2015 Summer Study on energy efficiency:

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