Apart from the 'performance gap', we now know how to achieve lower or even negligible energy consumption in buildings in the operating phase. However, the savings are clearly at the expense of building materials and their consumption of non-renewable primary energy ('grey energy') and associated greenhouse gas emissions. The final extent of building material consumption is influenced to a greater or lesser extent, favourably or unfavourably, by decisions reached in the various planning phases of a building. Progressive builders and planners often want to know how much environmental savings potential can still be tapped in specific planning phases through the use of alternative 'green' building materials. Alternative building materials therefore have little chance of being implemented, even though their use in load-bearing and non-load-bearing structures is becoming increasingly important as part of the Energy Strategy 2050. Moreover, an environmental assessment is hardly feasible under current conditions and their potential cannot be fully exploited.

The proposed project is therefore intended to pursue two objectives: (a) creation of benchmarks (incl. possible variations of primary energy sources and greenhouse gas emissions) for the construction of buildings in the respective planning phase, and (b) development of simplified procedures for measuring the volume of primary energy sources and greenhouse gas emissions for non-standardised building materials. For the preliminary study phase, MINERGIE-ECO projects will be evaluated on the basis of suitable key figures for the project. Case studies of different types of load-bearing structures will be used to show the savings potential that can be achieved in the preliminary design phase. Then case studies comparing the most common building components and materials with ecofriendly alternatives will be used to demonstrate the savings potential that can be achieved in the construction phase. Finally, case studies of interior fittings will be be used to demonstrate the savings potential in the implementation phase.

In addition to these evaluations, a methodology will be developed for simplified life cycle assessment of alternative (low-tech) and recycled building materials. This methodology will be applied to the design of new components, which offer the possibility of even lower environmental impact during the construction phase.

The results of the study will be presented in a report and condensed into a guideline in German, French and Italian on the optimisation potential of primary energy sources / greenhouse gas emissions in the construction of buildings and common components at different planning phases. The results of the study can also serve as a basis for updating life cycle assessment databases, developing alternative new construction solutions and as a starting point for specific additions to reconstruction procedures.