The "Efficiency House Plus" was officially opened by Chancellor Angela Merkel on 7 December 2011, following a year of previous planning and construction. The house is centrally located, at Fasanenstraße 87a, 10623 Berlin, near the Technical University of Berlin and close to Kurfürstendamm and can be visited before and after the use of the test family.
An Efficiency House Plus generates its own energy and makes it available to the residents or feeds the excess energy back into the public grid.
This specific house in Berlin also includes electro-mobility into the concept. As an Efficiency House Plus with Electro Mobility it creates energy and makes it available to the users and their vehicles. Excess energy can either be fed back into the public grid or can be stored in a house battery.
Note: The positive energy balance is required for both
- primary energy use and
- final energy use
The single-family house has a living area of approximately 130 m² with two storeys and was designed for a family of four. The "shop-window" in front of the building is meant for parking the vehicles and contains the charging infrastructure for the electric vehicles, an electric car and two pedelecs. The so-called "energy core" of the building is placed between the shop-window and the living area. The energy core includes the building service technologies, but also the wet rooms (bathrooms, kitchen, etc.).
-> Watch a 1-minute video on how the house functions
A key goal was to integrate the energy production technologies into the architecture. The simulation of the planners (architect Werner Sobek, Stuttgart) predicted that the roof (98 m² monochrystalline photovoltaic modules with an efficiency of about 15%) and the facade (73 m² thin-film module with an efficiency of about 12%) should produce about 16 MWh/yr electricity. According to the prediction, the house should use about 10 MWh/yr and the vehicles 6 MWh/yr.
The house is heated by a central heating system with an air-to-water heat pump. The delivery system to the rooms is a floor heating system. Additionally, a balanced mechanical ventilation system with 80 % heat recovery was installed. A building automation system measures and visualises all data centrally and transfers the data to an open source system that allows for targeted energy management. The users can communicate with the system via touch pads and smart phones.
A main part of the energy concept is the buffer battery, that ensures that the produced electricity can be used by the building itself. The battery has a storage capacity of 40 kWh and is made up of second-hand battery cells which were previously used in electric cars. This sustainable re-use is possible since batteries in electric cars already have to be replaced when the storage capacity is reduced to 80%, which is absolutely adequate for a second life in a stationary use. The prototype used in the Efficiency House Plus in Berlin is compiled of 7250 single second-hand battery cells.
-> See the scheme below which presents all the features of the building service system concept.
-> A flyer with information on the building in English can be found here.
Building envelope components
Besides low U-values of the building envelope components, the building also has minimized thermal bridges. The floor, the walls and the roof are made of timber panels.
|Component||Construction/Material||Thickness [mm]||U-value [W/m²K]|
|Wall (from inside to outside)||gypsum board||12.5||0.11|
|installation space with hemp matting||60|
|oriented strand board (OSB)||20|
|oriented strand board (OSB)||20|
|vertical lattice and air space||-|
|thin film PV modules||-|
|Window||window frames with triple glazing||-||0.70|
|Roof (from top to bottom)||structural protective matting made of recycled rubber||10||0.11|
|oriented strand board (OSB)||20|
|cellulose insulation||400 - 520|
|oriented strand board (OSB)||25|
|moisture adaptive vapour lock||-|
|Ground slab (from top to bottom)||wood panneling, floating installation||15||0.11|
|compensation layer (cork)||3|
|dry floor screed||25|
|wood fibre elements in aluminum casings for installation of the floor heating system||30|
|honeycomb element with filling||25|
|oriented strand board (OSB)||25|
|moisture resistant chipboard||15|
A distinctive feature of the house is that all elements can be separated and moved to another location or be disposed of after the lifetime of this particular project contributing to resource efficiency in the project.
From March 2012 to June 2013 a family was invited to live in the Efficiency Plus House, to test the functionalities and to gain experiences from the everyday use. Besides monitoring the building´s energy consumption and electricity production throughout the year, which was carried out by the accompanying research team, the family also documented their experiences in a blog on the project website.
-> Watch a 15-minute video with insights on the building construction, the test family´s experience and further information on the monitoring, the social evaluation and the efficiency house plus programme of the BMUB.
A workshop with the family, together with residents of other energy plus houses, showed that the family enjoys living in the building and also has the satisfaction of not having a bad conscience because of using energy. They enjoy using the e-mobility and have spent more than 8000 km with the car and more than 3500 km with the pedelecs. One of the specific challenges for the family was the ventilation system which is not manually controlled and thus transferred warm external air into the rooms in the summer.
For the technical monitoring, Fraunhofer IBP measures the monthly balances of the final energy use, the energy sources and energy consumers as well as the electricity production by the photovoltaic system, all in detail, and then compiles the measurements to cumulated energy gains and uses.
The BMVBS (BMUB) project website presents detailed monitoring results for:
- actual electricity values: actual energy production (pv system) and energy use for the heating/domestic hot water, lighting, household electricity, building service systems, e-mobility; also available on a daily basis
- actual indoor and outdoor climate: temperature, relative humidity, CO2-concentration
- actual temperatures of the heating and domestic hot water system and the ventilation system
- yearly energy balances: electricity generation of the pv system, cumulated annual energy gains and energy use, and monthly energy gains and uses.
-> Some graphical results of the technical monitoring are presented below.
First interim report after 12 months in an inhabited condition
The measurements show that despite unfavourable climatic boundary conditions, the energy production by the roof and facade integrated photovoltaic systems have been higher than the energy use by the building service system and the user-dependent energy use of the house. About 25% of the electricity need for the electric vehicles could be covered by the excess energy.
Under "normal" (average) climatic conditions, the house could have covered the whole electricity need for the electric vehicles and could have additionally fed excess electricity into the public grid.
-> Find the monitoring report by Fraunhofer IBP (in German language) here.
Annual energy data in detail
The whole energy use is based on electricity (electrical heat pump, pv, battery, household electricity). The electricity use can be separated into the following energy uses:
|Room heating via heat pump||4224||20.8|
|Hot water via heat pump||1641||8.1|
|Auxiliary energy (fans/pump/control)||3099||15.3|
|Household equipment and household processes||2910||14.3|
|Total house operation||12400||61.1|
Electricity use for project specific equipment (not used for house operation):
battery heating, battery ventilation, data processing unit and visualisation screen, waste pipe heating, LED lighting of the building core, external lighting, trenching pump, information screens)
Photovoltaic energy generation,
|used directly by the house||6555||32.3|
|fed into electricity grid||6751||33.3|
|Electricity taken from the grid||5845||28.8|
* The energy data in kWh/m²a is related to the so-called useful floor area A(N), a virtual floor area derived from the gross volume by multiplication with the factor 0.32. With the rather big volume of the house (rather high ceilings) the useful floor area is 203 m². It is thus bigger than the living area. A(N) is used as reference area for all residential buildings according to the German energy decree (EnEV).
With its “Future Construction” research initiative, the BMVBS promotes economy, science and society in the construction field during energy conversion. The research initiative comprises departmental and proposal research and the research promotion provided for Efficiency Houses Plus (a shared investment promotion provided by the Federal Government for technical innovation and its research support). The BMVBS supports the construction of buildings which produce significantly more energy than is required for their operation. The pilot projects are to be assessed within the context of a scientific support program. The results should aid in improving energy management in modern structures. In addition, the necessary components for an energy-efficient building shell and the utilization of renewable energy will undergo further development.
There is a specific calculation tool available for the assessment of efficiency plus houses that is based on DIN V 18599. It adds a certain energy use for household electricity and balances the sum of energy needs with the energy generated by a photovoltaic field or wind generators. The tool is available in German and is called Effizienzhaus-Plus-Rechner and can be used at www.effizienzhaus-plus-rechner.de.
Energy performance certificate for efficiency houses plus
This certificate is added as an additional document to the regular German energy performance certificate. On the right side of the document there are black arrows showing the energy performance using the regular energy performance boundary conditions and on the left side there are blue arrows showing the primary and final energy surplus of the house under the boundary conditions of efficiency houses plus. They take into account household energy use and all energy generated at the building including the electricity that is fed into the grid. The certificate of the house in Berlin is presented in a graphic below. Please note: The certificate is based on calculations and presents thus slightly different values than the measured data in the table above.