An apparatus and corresponding method measure physical parameters using a plurality of low-cost sensors coupled in series is provided. These sensors can be thermal sensors for measuring the temperature of a heating pad. Different types of sensors to measure temperature, moisture, pressure, or state change of a switch may be employed. Such sensors may be distributed throughout a building to concurrently monitor multiple physical parameters at numerous locations. The sensors are easily manufactured, thus reducing sensor cost. Costs are further reduced by the use of two wires to connect the series of sensors. Moreover, the wires can be run easily through conduit or cable troughs.