This research has examined the system effectiveness for sprinkler systems, alarm systems and stairwell pressurisation systems. The focus has been on systems for multi-storey commercial and residential buildings. The analysis has used a combination of published reliability data, calculated availability ranges, industry information, and system survey information. Fault trees have been used to describe the relationship between different aspects of system effectiveness and to quantify for generic design types the expected value, and upper and lower bounds of system effectiveness.