Applications of decision analysis in the assessment of energy technologies for buildings

The transition to sustainable energy system calls for changes in both the production and consumption of energy, including issues such as the implementation of sustainable technologies and practices for energy conversion and the improvement of energy efficiency at the demand side. This Thesis i) identifies the need of decision support in the commercialization of sustainable energy technologies in buildings, ii) characterizes decision-making problems related to the above context, iii) develops and implements a methodology to assess energy technologies for buildings, and iv) presents two fields of application where the above assessment is essential. The decision-making problem is characterized by i) multiple objectives, ii) several interest groups with different preferences, iii) new alternatives with the lack of operational experiences and thus plenty of uncertainties, and iv) a broad portfolio of applicable technologies that have to be combined into a workable entity. Hence, an interdisciplinary decision support framework is required that combines basic theories of life cycle and decision analyses including sensitivity assessments. In this Thesis, the above methodological framework is implemented in terms of two applications: i) the assessment of heating systems for a single-family house and ii) the selection of technology portfolio in a retrofit project that results in improved energy efficiency and thermal comfort, and reduced environmental burdens. Specifically, the competitiveness of a natural gas heating system containing a solid-oxide fuel cell (SOFC) is examined with respect to residential heating systems containing no electricity generation. Moreover, a multi-criteria portfolio model is applied to determine the most preferred retrofit measures in an apartment building. The above examples are selected because i) they represent a new field of research and ii) they are interesting due to the challenges they provide in decision-making. In the assessment of heating systems that incorporate new technologies, the mutual ranking of alternatives often must be established on the basis of incomplete information. Here, the extensive framework of decision-making was useful. In the second application, the multi-criteria portfolio model was suitable in the search of optimal technological solutions in retrofit projects. According to computational studies, a small (1 kWe) SOFC heating system is an attractive alternative to traditional heating systems and simple, inexpensive measures with good price-quality ratio were preferred as retrofit actions. While the methodological framework is generally applicable, the computational examples are mainly indicative and illustrative.