Fire alarms work together with fire sprinklers. Technically, you could have one or the other…but the advantage of having both outweighs the benefits of having just one in any space.
Fire alarms notify people by sounding the alarm, but that does not ensure the safety of your home. Why? Because fire sprinklers are not installed and therefore if no one is in the building/home, the alarm could go on and on but the fire will also keep spreading. Likewise, a fire could break out in the middle of the night but no one is notified when it happens because of the absence of fire alarms. By the time that someone notices it, smoke could have been inhaled and it would be harder to escape the building/home. Every second counts during a fire and it is important to be notified as soon as possible.
It is important not only to be alerted when there’s a fire, but also to have the resource available to extinguish it.