A concept of a flow sensor optimized for the use in HVAC (Heating Ventilating Air Conditioning) systems is presented. The fabrication of the transducer is based on PCB (Printed Circuit Board) technology to keep costs low and allow for easy handling and replacement. The complete sensor device consists of a quantizer, a conversion circuitry, and a network link. Through interaction with the streaming fluid, the transducer generates an electrically measurable signal which allows determination of the total flow of the fluid. The measurement principle is based on a modification of the calorimetric principle. Hence, miniaturized heat sources and nearby temperature detectors have to be implemented. The behavior and performance of the sensor concept has been studied by means of finite element simulations. The quasistatic and transient simulations reveal the temperature allocation inside the sensor and the surrounding fluid and therefore allow a further optimization of the sensor for different applications.