The Door Lock System automatically senses heat from fire or actuated by current from the smoke detector due to the shape memory alloy (SMA) spring that acts as both actuator and sensor for the door locking mechanism. SMA is a smart material that contracts when heated above its activation temperature. SMA also has resistance properties that enables it to be actuated by joule heating. When electric current flows through the wire, it can generate heat to cause the phase transformation. This device is a green innovation as it doesn’t require added power supply. Instead the heat from the environment and also existing power supply from the smoke detector can be used to actuate the door lock system