An interdisciplinary analysis of heat energy consumption in energy-efficient homes : essays on economic, technical and behavioral aspects
- Eine interdisziplinäre Analyse des Heizenergieverbrauchsverhalten in energiesanierten Wohngebäuden: Aufsätze zu ökonomischen, technischen und Verhaltens-Aspekten
Heesen, Florian; Madlener, Reinhard (Thesis advisor); Thomes, Paul (Thesis advisor)
Dissertation / PhD Thesis
Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2019, Kumulative Dissertation
The dissertation offers new insights on heat energy consumption in residential buildings, delivering explanations on the most energy intense consumption process in private households. Each chapter sheds new light on economic, technical and behavioral aspects as well as the transdisciplinary dependencies of heat energy consumption. This thesis analyzes heat energy consumption from the consumer’s perspective. Thus, holistic insights into the energy consumption behavior of one of the main stakeholders of the German "Energiewende" are gained. The three different disciplinary perspectives on heat energy consumption are explored through four research questions. The first research question addressed is whether economic aspects affect short-term, less conscious behavior in the same way as long-term, more conscious behavior. The model proposed is based on Becker’s household production theory and integrates economic, engineering and behavioral elements. Comparative statics enables a multidisciplinary integration of (a) price- and income- functions to cover economic influences, (b) the production function to cover technical influences, and (c) the utility-based choice architecture. Based on a functional representation of the household production theory, a panel data model of heat energy consumption is estimated. The empirical analysis is based on field experiment data from 60 adjacent apartments in South-West Germany. The analysis finds empirical evidence that the price elasticity of demand is only statistically significant when using yearly aggregated data. This result provides evidence that occupants apparently do not act upon energy price signals when following their daily home heating routine. However, occupants consider the fuel price in their heat energy consumption in less frequent cycles, as e.g. according to their yearly billing. Furthermore, addressing the 2nd research question based on the same model, data and methodology as the first research question, it becomes apparent that the price impact is less pronounced than the impact of comfort conditions. The 3rd research question of this thesis devotes attention to the difference between upfront-calculated energy performance ratings and realized heat energy consumptions. From an energy and environmental policy point of view, deviations of energy consumption from ex ante calculated energy performance ratings are problematic, as they jeopardize the meaningfulness of the ratings and thus deliver poor guidance for (prospective) homeowners, policy-makers and researchers alike. The reported gaps between energy performance rating and heat energy consumption are, apart from deviations from the mean aggregate values (i.e. heterogeneity), often attributed to anticipated or unanticipated behavioral effects. The related literature almost entirely treats building-specific energy performance ratings as universal standards, trying to explain the empirically observed discrepancies. This thesis investigates to what extent the current energy performance rating scheme in Germany can address behavioral issues. To this end, the empirical investigation applied sheds light on the deviations between energy performance ratings used in the regulatory norms and the heat energy consumption levels observed. Evidence is provided that it is not necessarily the behavioral dimension, but rather the static and mostly technically guided calculations of the energy performance ratings itself that account for the major part of the deviations. This leads to the conclusion, that there might be a need for further improvements in the field of energy performance rating calculations and methodology. The 4th research question addressed by this thesis separates energy service demand from the heating systems capabilities with regard to the acceptance of advanced heating systems. On the basis of Davis’s technology acceptance model, an energy technology acceptance model is introduced and tested on the basis of questionnaire data from the field experiment. The statistical inference is based on a partial least squares path modeling approach. The study suggests that attitudes towards acceptance of such systems are influenced by a system's perceived ease of use and the perceived thermal comfort delivered by it. However, we find evidence that the user does not perceive either of these influences directly. The analysis shows, that the variables perceived ease of use and perceived thermal comfort are mediated through the latent construct "perceived usefulness". The results suggest that in order to maximize the technology acceptance of advanced heating systems, measures need to target both, an easy-to-use system and the perceived thermal comfort. Overall, this thesis provides a holistic overview on the state of the art research and closes research gaps on heat energy consumption in private households. Each research question is analyzed thoroughly, results are discussed and concluding remarks are derived. The thesis thus provides insights and guidance on heat energy consumption and its interdisciplinary research to researchers, policy-makers and other stakeholders concerned with the German "Energiewende".