Cheaper insurance premiums for apartments which have sprinklers?  I challenge you to prove your claim by providing examples of insurance premiums which are currently lower for buildings with sprinklers, or where premiums were lowered in any particular building after it was retrofitted for sprinklers.  I agree that insurance premiums are a good measure of the actual value of improvements like burglar alarms, smoke detectors ... and sprinklers.  If there are any actual discounts for sprinklers, I'll bet they are just as minuscule as the discounts for smoke detectors and burglar alarms.