In this paper capacitive human detectors using the novel concept of so-called 'opened electrodes' are introduced. These types of detectors have been designed for interactive art application in normal living environments where the electrodes can be integrated, for instance, into the walls, floor and ceiling. Three different examples of these detectors are presented. In all of these detectors the human body acts as a moving electrode that modifies some capacitances in the detector system. The presence and position of a person within the range of 2 m have been detected using perpendicular electrodes. In addition, a tracking area of 2 m x 2 m has been achieved using uniplanar electrodes. The sensitivity of these detectors for the estimation of a person's position has experimentally been investigated and analyzed using simple intuitive circuit models. These models are required in order to develop calibration methods and measurement techniques that reduce the effects of the main parasitic capacitances, and improve the estimation of the person's position.