Real estate is considered more and more as an asset class that has to compete with other financial investment options like stocks and bonds. Additionally, real estate is often included in multi-asset portfolios for diversification purposes since academic research suggests that real estate investments are not highly correlated with stocks and bonds. For this reason the valuation and investment performance measurement of large real estate portfolios has become an issue. Furthermore, corporations and corporate managers begin to realize the resource value of operational building assets and their contribution to business profit. The effective use and management of operational building assets requires the assessment of building performance not only in financial terms but also by using performance indicators that depend on the mission and on the objectives of the organization. Therefore a wide range of methods and frameworks for performance measurement of real estate assets have been developed. These methods range from the detailed technical assessment of buildings to surveys of user satisfaction or of serviceability of the building assets (McDougall et. al. 2002; Szigeti and Davis 2001).