Buildings that are cooled and, if applicable, heated by thermo-active building systems (TABS) in combination with environmental energy have been established in the market during the last years. Many successful and efficient examples prove, that these systems can achieve a good thermal room comfort with a high energy efficiency of the plant system using environmental energy (mainly surface-near geothermal energy). However, operating experience and a systematic evaluation of several building projects demonstrate that there is potential improvement in the design, implementation, and operation of TABS systems. The article presents operating experience and a detailed evaluation of the operation performance of several non-residential buildings with thermo-active building systems with respect to thermal comfort and energy efficiency.
