CO2 balancing and optimization of building structures

Based on current knowledge, it is estimated that more than 50% of global CO₂ emissions are attributable to the construction industry, with approximately two-thirds of these emissions coming from the building construction sector. The construction industry—and building construction in particular—therefore plays a central role in averting climate catastrophe.

Savings achieved to date have focused almost exclusively on energy consumption during building operation. Based on the Energy Conservation Act of 1976, the Thermal Insulation Ordinance was first introduced in 1998, followed by the Energy Conservation Ordinance (EnEV) in 2002, which was regularly updated (2004, 2007, 2009, 2014, 2016) and were replaced in 2020 by the Building Energy Act (GEG). However, these regulations focus exclusively on the operation of buildings. As a result, energy standards for the building envelope have now reached such a high level that no further CO₂ savings are expected from building operation in the future. Consequently, the focus is increasingly shifting to the CO₂ emissions resulting from the construction of a building (as well as its maintenance and subsequent demolition)—the so-called “gray emissions.”

Based on the volume of construction planned in Germany over the next few years and the remaining CO₂ budget of approximately 4 gigatons of CO₂—as determined by the German Advisory Council on the Environment to meet the goals of the Paris Climate Agreement—researchers at the University of Stuttgart (Weidner, Sobek et al.) determined that only approximately 35 kgCO₂ may be emitted per cubic meter of enclosed space. However, preliminary studies conducted at Kiel University of Applied Sciences show that buildings constructed using conventional solid-core construction methods currently require approximately 125–165 kg CO₂ per cubic meter of enclosed space over a lifespan of about 80 years. A significant portion of this consists of energy-independent, process-related CO₂ emissions, which cannot be eliminated even with an increase in the share of renewable energy in power generation. CO₂ consumption must therefore be drastically reduced in the future—by approximately 75%.

As part of this research project, the aim is therefore

1. comprehensive CO₂ life cycle assessments will be used to provide an overview, transparency, and empirical data regarding CO₂ consumption over the life cycle of typical building structures;
2. based on the CO₂ life cycle assessments, the key factors influencing CO₂ demand will then be identified; and
3. specific measures will be developed to reduce the CO₂ demand of building structures by an average of at least approximately 30% in as cost-neutral a manner as possible; Ideally, (in conjunction with a higher share of renewable energy in the future), the required lower limit of 35 kgCO₂/m³ of enclosed space should be achieved.