Thus, sensors deemed necessary can vary based on the functionality and features of hazard detection system 205. In one embodiment, hazard detection system 205 can be a combination smoke, fire, and carbon monoxide alarm system. In such an embodiment, detection system 205 can include the following safety sensors 221: a smoke detector, a carbon monoxide (CO) sensor, and one or more heat sensors. Smoke detectors can detect smoke and typically use optical detection, ionization, or air sampling techniques. A CO sensor can detect the presence of carbon monoxide gas, which, in the home, is typically generated by open flames, space heaters, water heaters, blocked chimneys, and automobiles. The material used in electrochemical CO sensors typically has a 5-7 year lifespan. Thus, after a 5-7 year period has expired, the CO sensor should be replaced. A heat sensor can be a thermistor, which is a type of resistor whose resistance varies based on temperature. Thermistors can include negative temperature coefficient (NTC) type thermistors or positive temperature coefficient (PTC) type thermistors. Furthermore, in this embodiment, detection system 205 can include the following non-safety sensors 222: a humidity sensor, an ambient light sensor, a push-button sensor, a passive infra-red (PIR) sensor, and one or more ultrasonic sensors. A temperature and humidity sensor can provide relatively accurate readings of temperature and relative humidity. An ambient light sensor (ALS) can detect ambient light and the push-button sensor can be a switch, for example, that detects a user's press of the switch. A PIR sensor can be used for various motion detection features. A PIR sensor can measure infrared light radiating from objects in its field of view. Ultrasonic sensors can be used to detect the presence of an object. Such sensors can generate high frequency sound waves and determine which wave(s) are received back by the sensor. Sensors 220 can be mounted to a printed circuit board (e.g., the same board that processors 210 and 230 may be mounted to), a flexible printed circuit board, a housing of system 205, or a combination thereof.