It is widely recognised that buildings play a significant role for sustainable development and are a key factor to the future success of the sustainability movement in general. As shown in a preparatory report of the United Nations Environment Programme (UNEP) (Levine et al., 2007), worldwide building-related CO2 emissions (including electricity usage) are expected to grow from 8.6 billion tons in 2004 to 11.4 billion tons in a low-growth scenario, or up to 15.6 billion tons in a high-growth scenario, by 2030. This represents approximately 30% of global anthropogenic emissions. However, with commercially available technologies, the energy consumption in both new and existing buildings could be reduced by an estimated 30%–50% (Cheng et al., 2008, Laustsen, 2008). These numbers demonstrate the high impact the building sector has on the environment, but also the corresponding potential for improvement. There is an evident need for an increased share of sustainable buildings.

To achieve this, it is necessary to motivate the stakeholders of the building sector, such as real estate investors, to opt for more sustainable building solutions. Within this research work the motivating factors for sustainable construction are established, such as financial benefits, and are subsequently described and empirically proved. This should encourage the willingness of commercial property investors to invest in sustainable properties.

Financial profits can be derived in different ways. They can be achieved through cost savings or increased income. They can take place directly on a building level, through lowered construction and operation costs or increased rental prices, or indirect through the effect the building can have on its environment and occupants, such as lowered emissions or increased productivity.

The presented research work addresses all the financial effects of sustainable building but especially focusses on increased rental prices and productivity gains. Linked to this research are two empirical studies that provide the basis for the analysis of financial effects for commercial real estate investors in Switzerland. Thus, the focal point will be on the Swiss real estate market.

The chosen methodology in this thesis is based on applied research. This is due to the general character of the research work and the described research questions and hypothesis, which have high practical relevance and are less theoretical in

nature. Following this research approach, the methodology is based on defined research questions and hypotheses (Dunleavy, 2004).

Due to the trans-disciplinary nature of the research questions, a variation of qualitative and quantitative methods is applied. Using a so-called mixed method approach, a literature review, structured interviews, questionnaires and statistical analyses are combined to generate the final research results. This combination of different analytical methodologies follows the idea of triangulation.

The written thesis is a paper dissertation that consists of four journal papers. In addition, there is an introduction and a synthesis section in order to frame this combination of papers.