Improvements in a smoke alarm are presented. The multifunction smoke alarm unit includes separate sensors within a single enclosure for detecting smoke and occupancy, sounding a distinctive audible alarm when combustion is detected or the presence of a person within the area of the sensor. The multifunction smoke alarm can replace an existing single function smoke alarm. Multiple multifunction smoke alarms are networkable together for various purposes. Additional features include intruder alarm, visitor annunciator, integrated illumination source, external lighting control, HVAC system control, ceiling fan control, ventilation control, and/or fire safety system control. The proposed multifunction smoke alarm provides much-needed improvements for security, energy saving, safety, and user convenience without the need for completely separate systems for each purpose.