DEKASYS

The building sector is a major contributor to greenhouse gas emissions, both in Germany and globally. While achieving Germany’s climate protection targets requires an energy retrofit rate of at least 2% of the building stock per year, the current rate remains below 1% and has stagnated despite a variety of political strategies and instruments. Although numerous studies have addressed the question of how to increase the dynamics of energy retrofit, there is a lack of deeper systemic understanding of the motivation and decision-making processes of homeowners as key actors in the renovation process.

The most important findings derived from systems analyses, expert involvement, and surveys of homeowners are summarized as follows:

a) From interviews with experts:

• The transformation process towards a climate-neutral building stock is highly complex but is usually examined from a technical and economic perspective, with little consideration of social complexity—for example, the heterogeneous decision-making behavior of condominium owners or unintended social side effects of policies
• Extensive knowledge from behavioral sciences—such as risk aversion, non-rational human behavior, decision-making under limited information, the influence of media and social environment, value orientations, and cognitive overload—is rarely applied in political practice, partly due to a lack of corresponding expertise
• Experts involved in the validation process possessed extensive, but highly fragmented knowledge regarding technical, economic, ecological, or social components of the heat transition, reflecting the complexity of implementing energy retrofits
• Integrating heterogeneous expert knowledge into system maps and co-creative exchange formats represents a promising approach for the more holistic development of policy strategies and instruments.

b) From the systemic decision models:

• Causal loop diagrams are highly suitable for visualizing complex decision-making processes while incorporating a variety of decision-making and behavioral theories
• Numerous reinforcing feedback loops through word-of-mouth, media, and social networks were identified, highlighting the importance of positive public discourse and social environment on individual motivation for energy retrofits
• Balancing feedback loops were particularly observed with respect to the availability of sufficient capacities among craftsmen, planners, and energy consultants. This indicates that increasing decision-making dynamics for energy retrofits in society may be dampened by long waiting times or higher costs resulting from limited implementation capacity.

c) From the survey of homeowners:

The results clearly indicate that homeowners’ decisions to undertake an energy retrofit are highly complex, individual, and strongly context-dependent. It should be noted that the participating owners (respondents) were predominantly male (over 80%), over 60 years old (over 60%), and 80% owned a single-family home. Twelve percent owned fully renovated properties, 58% partially renovated, and 40% unrenovated properties. Among respondents with fully renovated homes, 97% were satisfied with the outcome, with 63% being very satisfied.

The primary motivation cited was a reduction in heating costs, followed by an increase in property value, personal contribution to climate protection, and improved living comfort. The most frequently mentioned barriers were high financial burden of renovation, the complexity of existing funding schemes, shortage of skilled craftsmen and planners, high effort required to acquire knowledge for implementing renovations, and bureaucratic hurdles related to renovation implementation. These correspond to the five most frequently cited barriers in order of mention.

Based on the previous investigations, the following recommendations have been derived to accelerate the dynamics of energy retrofits:

• Greater consideration of social complexity and psychological insights into human behaviour in political practice, particularly in the development of policies and policy mixes
• Promotion of a positive public discourse on energy retrofits and the heat transition, especially through media and political actors
• Stronger differentiation in the development of policies according to target groups, particularly with respect to ownership types and household income levels
• Reduction of homeowners’ perceived complexity regarding energy retrofits
• Simplification, stabilization, and socially equitable design of the funding landscape
• Reduction of renovation costs through lowering regulatory requirements and creating greater flexibility in the renovation process

Consideration of sufficient capacities in consulting, planning, and skilled trades to accommodate future high dynamics of energy retrofits.

In the year 2026, the systemic decision models will be expanded to include property owners in condominium owners’ associations and owners of multi-family buildings. In a final workshop with the experts from politics, academia, and practice who participated in the model validation, the recommendations derived from systems analyses and surveys will be discussed and ultimately consolidated into a policy paper.

Schünemann, C. (2025). Erhöhung der Dynamik energetischer Wohngebäudesanierung—Befragungsergebnisse zu Motivation, Hemmnissen und Lösungsansätzen für verschiedene Eigentumsverhältnisse in Deutschland. Social Science Open Access Repository. doi.org/10.26084/8056-2f80

Schünemann, C., Dshemuchadse, M., & Scherbaum, S. (2025). A systemic decision-making model for energy retrofits. Buildings & Cities, 6(1), 511–526. doi.org/10.5334/bc.534

Schünemann, C., Sidorova, A., Gkini, C., & Kopainsky, B. (2021). Using system dynamics modelling to analyse the interplay of policies and societal motivation for promoting energetic renovation. 2021, 30. proceedings.systemdynamics.org/2021/papers/P1157.pdf