What a BuildTog is

BuildTog 1st generation

BuildTog (Building Together) is a European Passive House project initiated by four partners who are engaged in sustainable construction: The European housing companies network EURHONET, the French architect Nicolas Michelin (A/NM/A), the German energy consultancy LUWOGE consult and the worldwide leading chemical company BASF.

The target of BuildTog is to develop a generation of Passive Houses that are in the same time energy and economy efficient and also architectural ambitious. In this sense it is a very practice oriented research project. BuildTog houses will be constructed in Passive House standard. They are very efficient and fulfill the EU energy saving targets which will influence the standard of all new buildings in future.

BuildTog Passive House projects are respecting a standardized planning methodology developed by LUWOGE consult during the course of the project to control the detailed requirements concerning energy related specifications and construction costs from beginning on. The first generation (2009-2015) followed consequently the Common Design developed by the French Architect Nicolas Michelin (A/NM/A), which he adapted together with the local planners to each site (Local Adaption).

To ensure the energy performance and the planning process LUWOGE consult attended all projects up to the certification. A/NM/A checked the design in several planning phases and saved the quality of architecture. BASF took care for having available their proved system solutions in all participating countries. The housing companies continuously controled planning, construction and use of their BuildTog´s (monitoring) to optimize the processes. To initiate a smooth know-how transfer and to reach the European energy targets all results will be published on www.BuildTog.eu.


The European Union intensifies her energy saving targets in construction sector year by year. By 2020 the CO2 emissions of residential buildings have to be reduced up to nearly zero. Even if the housing companies organized in EURHONET were already engaged in development of sustainable housing concepts they didn´t feel well prepared for the future EU requests.

That´s why they decided to set up a project to gain experience together in construction of energy efficient apartments and to share their knowledge. Currently EURHONET consists of more than 30 housing companies from 5 European countries (Sweden, United Kingdom, France, Germany, Italy). Together they manage about 700.000 dwellings and construct more than 15.000 new each year.

Project partners

EURHONET arranges frequent workshops to optimize the work flow of their member companies in different topics relating housing industry. In the context of their Energy Savings Topic Group the BuildTog project was developed to find a common process for planning and construction of sustainable housing. BASF is a strategic partner of EURHONET´s Energy Savings Topic Group. As leading producer of raw material, system solutions and end products for the construction industry the company wants to contribute energy efficient construction and to participate in the development of new innovative solutions.

LUWOGE consult, the energy consultancy of BASF´s own housing company BASF Wohnen + Bauen, was intensively engaged in activities to increase the energy efficiency in refurbishment and new construction since years. In collaboration with international partners know-transfer programs are generated to multiply sustainable building concepts in a large scale.

A/NM/A, the office for architecture and urban design of Nicolas Michelin, based in Paris, was already working together with some EURHONET members in the realization of French “Eco Quarters”. Within the scope of their building concepts the planners try especially to integrate the local situation into their architectural design and to develop concepts for natural ventilation.

Building together

Exchanging intensively their experience in reaching the same targets in construction projects on different European sites the participants want to study, how it is possible to devolve their high expectations to the energy performance of residential buildings economical efficient, without accepting deductions in building design. By the repeated use of a together developed methodology it is simple to demonstrate, which influence on the building construction is taken by change of framework requirements. That way the participants are sensitized for details and understand how to contribute the emergence of specific local features for their BuildTog housing. In each country up to three projects will be realized to point out regional characteristics.

All participants meet three times a year at the different locations. They report about the progress in their projects and deepen their knowledge in energy efficient construction in lectures and common workshops. They become acquainted with the sites, problems and solutions of their fellows and can inspire each other in optimizing their buildings.

Common design


At the beginning of the project in 2009 the participants analyzed their current housing typologies and looked for analogies. The description of a common building concept resulted out of that. Because the national requirements for building energy performance and their calculations are very different in each country the international respected Passive House standard was defined as target.

Based on the common specifications in accordance with LUWOGE consult A/NM/A developed a linear, 4 story building with pitched roof. The 2 middle axes were moved to the front. The façade in this area was slightly angular and clearly heightened. Thereby space for staircases and common infrastructure was generated in the buildings backside and for outside areas next to the apartment in the front.

In first and roof level there was some space for additional use which could be inside our outside of the thermal volume. Because of reserves to the supposed design restrictions in Passive House planning the participants consciously decided to pass on the optimization of building compactness. Therefore they proposed to construct the buildings without cellar, South - oriented and as far as possible without shading from outside.

The common design was possible to be realized with four or five dwellings per story, three to four levels plus roof, free-standing or attached. The apartments above were usually planed as duplex to have a varied mix of all together about 15 dwellings with 2 to 5 rooms.

In the context of pre design the teams from A/NM/A and LUWOGE consult develop together with the housing companies and their familiar planners a local adaption of the common design. They had to respect numerous aspects like climate, building law, building construction, building technology, culture and others. Because the same type was always basis of the local adaptation the participants also could revert to solutions of their project partners. Thereby the BuildTog could be optimized in an iterative process step by step.

To assure the quality of planning LUWOGE consult attended all BuildTog projects up to their finalization and supported the local planners according to their background of experience in energy related calculations, detailing of connection points and selection of Passive House components. A/NM/A controled the architectural transformation of their design by the local architects before building application and start of construction side.

According to German regulations the project is structured into 9 phases which usually have to be adapted to the planning process in other countries. Step by step all participants are introduced into the next phases by LUWOGE consult and experienced local BASF employees, who are at home in construction industry. During workshops different work packages are allocated and responsibilities are defined. Upon completion they all have a common closure and start into the next phase together.

All planning results are documented phase by phase. In course of time a substantial planning tool is developed which can be used by all participants also in future projects. The guideline fills with different and more and more optimized solutions for the most important questions from project to project. To simplify the complex PHPP calculation an additional file is developed as navigation element to visualize fast and easy the optimization potential. Other Excel-based tools are added like the calculation of economy and life cycle costs.

Outside of Germany the availability of Passive House components has to be partly improved. As an industry partner BASF is interested in offering international proved system solutions and to push new innovations. The Passive House certification is prepared by LUWOGE consult and enforced by Passive House Institute, Darmstadt. Also the certification process is going to be optimized in replication.

Already during the planning phase the housing companies agreed on a common monitoring concept to be able to compare the results based on the same kind of data. In main focus is the optimization of the technical equipment in running process. Those who have no experience in measuring user behavior in Passive Houses will also work on that.


Originally it was planned to construct BuildTog houses without cellar, South-oriented, free standing in the green fields only. Very soon it was clear that other things are more important to choose a site than energy related topics. Meanwhile there are designs for BuildTog houses under various boundary conditions. So it is possible to demonstrate that energy efficient buildings can be constructed in nearly every situation.

In Germany and France two BuildTogs are already completed, three more are in planning in France, one in Germany and another one in Sweden. Moreover there are contacts in additional countries to partners outside from EURHONET. Requests from further countries are very welcome.

BuildTog++ new generation

Based on the positive experiences from the first BuildTog phase between 2009 and 2015 the project framework will be improved for a wider future dissemination. The adaptation of a common design on 7 different sites was very helpful to get a clear understanding of the most critical issues in Passive House planning. The results can be compared and evaluated on a common base now which leads to general awareness about affordable, efficient but also well designed constructions.

The new BuildTog++ generation will follow a common methodology without strict design rules. The architectural quality will be ensured by the project process. Other building sizes, typologies or uses are possible to be implemented from now on. It is also planned to consolidate the Euronet energy saving groups for new construction and retrofit to adapt the process for building optimization also to refurbishment.

In the beginning of 2015 the application for a deeper research in the framework of HORIZON 2020 was initiated. BuildTog++ then has to be improved into plus energy standard on a district level by the use of renewable energies. The already existing pilot projects demonstrated that it is possible to construct a similar building from 115% up to 85% of the average construction costs depending on the project boundary conditions.

Conscious and appropriate action is hindered in the very complex integrated planning and construction process by a huge lack of knowledge on all decision maker levels. Therefore a clear methodology with simplified and easy to use methods and instruments has to be developed and offered.

Join BuildTog

For all EURHONET members the main benefit of participating in BuildTog is to become skilled in applying high energy performanced buildings to be prepared for the future European nearly zero energy standard from 2020 on.

We are looking forward to hearing from further housing companies or investors interested in joining our BuildTog project.

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