A low-cost, compact indoor thermal environment monitor

An environment monitor is developed to assess the thermal condition in living and working atmosphere in terms of room and radiation temperatures, relative humidity and air flow. Thermistors are used for temperature and air-flow detection, and the polyimide-film-based capacitive sensor is used for relative humidity detection. To achieve high-accuracy measurements with these low-cost sensors and their simple electronics, calibration table made by interpolating calibration data using cubic spline functions are accommodated into the smart transducer interface module. The module also includes the electronic data sheets of sensors and the communication facility for networking. Performances of prototypes demonstrate the validity of the present approach to a low-cost high-accuracy thermal environment monitor.