In order to reach carbon neutrality, GHG emissions from all sectors of society need to be strongly reduced. This especially applies to the construction sector. For those emissions that remain hard to reduce, removals or compensations are required. Such approaches can also be found within the built environment, but have not yet been systematically utilized. This paper presents a review of possible carbon storage technologies based on literature and professional experience. The existing technologies for storing carbon can be divided into 13 approaches. Some are already in use, many possess the potential to be scaled up, while some presently seem to only be theoretical. We propose typologies for different approaches, estimate their net carbon storage impact and maturity, and suggest a ranking based on their applicability, impact, and maturity. Our findings suggest that there is an underutilized potential for systematically accumulating atmospheric carbon in the built environment.

One of the main objectives facing climate protection targets is how to deal with the existing building stock. Refurbishment measures are essential to ensure sustainable urban transformation. Life cycle assessments (LCAs) enable refurbishment measures to be evaluated holistically at the environmental level. However, there is still no sufficient methodological basis for the uniform evaluation. This present paper proposes a new perspective for comparing the continuing use with refurbishment as well as the demolition and new construction of a building. Thus, two new indicators are presented and elaborated regarding refurbishment measures: sustained emissions and the avoidance potential. To verify and validate the newly developed methodology, we implement it as part of this case study. We compare the environmental impact of a building’s continuing use with refurbishment measures as well as demolition and a replacement building with functional equivalence. The results indicate the environmental benefits of refurbishment measures compared to other approaches towards existing buildings. Although new buildings typically possess a superior energy standard, nevertheless, irrespective of the major impact of operational energy, refurbishment measures appear to be the most viable option for dealing with existing buildings over their life cycle.

Environmental impacts of new construction in the built environment have been determined for considerable time using life cycle assessments (LCAs). However, the significance of the existing building stock is neglected when considering environmental impacts at the level of embodied energy. Today alone, most of the buildings that will remain in place in 2050 are already in existence. For achieving national and international climate protection goals, the LCA of refurbishment measures is crucial. Thus, the link between building LCAs, which are conducted based on EN 15978, and refurbishment measures is established and ultimately transferred to the neighbourhood level. This paper provides a methodology in accordance with applicable standards to make use of a large activation potential in neighbourhoods. An initial focus is on the survey of the area to be investigated. The subdivision and typologisation of the building stock based on established toolboxes within the neighbourhood as well as the description of the implemented measures are besides in the focus of the methodology. Multiple scenarios for existing buildings in the neighbourhood combined with a consistent framework enables LCA to be conducted. The connection of the spatial component by a demarcated neighbourhood and the connection with the structural dimension by buildings enables a holistic view of refurbishment measures in the urban environment. As a link between the individual building and the municipality, the neighbourhood serves as a meso level.

Life cycle assessment (LCA) in the building sector has become a widely used method for quantifying environmental impacts of a building over its entire life cycle. Currently, however, no standardized procedure exists for considering refurbishment measures. In addition, the LCA, according to the European standard EN 15978, is limited to building level only. This paper shows how a~methodological LCA framework of refurbishment methods can be applied at three levels: single building, neighbourhood, and municipality. Initially, the proposed methodological approaches are introduced while the framework rules are defined for each of the three levels. The system boundaries of the LCA differ regarding the assessment levels within the given methodology and are adapted accordingly. In addition, the three levels of assessment are defined by the accuracy of measurement results, and data requirements, as well as by the specific value of the calculations and the ownership of the building stock. The assessment levels provide a specific quality and quantity of environmental indicator results. Thus, the complex interrelationships of the assessment levels are shown. The developed framework for the environmental assessment of refurbishment measures provides comparability at the building level. At the neighbourhood level, emissions from refurbishment measures are compared with the reductions of emissions through heating energy demand. Ultimately, the potential of refurbishment measures at the municipal level can be identified on a large scale and used as a decision-making tool.