MERGENTHALER defines itself as one of the most future-proof office buildings and a truly pioneering project: ESG principles were consistently implemented in both the planning and refurbishment phases. The resource-saving construction method and the use of sustainable building materials contribute to MERGENTHALER having 42% lower CO2 emissions compared to a new building.  The building was completely gutted and a new, energy-efficient façade was erected. The energy balance is further improved by a specially designed extension, which also adapts the floor plan of the future office space to contemporary requirements. The structural expansion of the building is a special example of the creative mix of old and new. With its focus on a holistic revitalization approach, sustainability, and innovation, MERGENTHALER in Eschborn is a model for dealing with existing buildings. The use of geothermal energy means that the building can completely dispense with the use of fossil fuels.