This book presents the influence of the energy certificate on the real estate industry, particularly on property valuation, and how the energy certificate can be quantitatively and transparently integrated into various valuation methods. The key question in this study is whether the operating costs associated with the energy certificate are relevant for property valuation and whether potential tenants or owners will consider this aspect when selecting a property in the future. Comprehensive literature research is used to highlight and analyze existing findings. Based on these findings, further work is conducted through surveys of market participants (owners in self-use, landlords, and tenants). Since there are no experiential values regarding the energy certificate yet, the survey was carried out.