Fire safety engineers endeavour to ensure that a design achieves an adequate level of fire safety. For uncommon buildings, adequate safety cannot be based on precedent and an explicit evaluation of the adequacy of proposed safety features may be required. Commonly, this requires demonstration that the residual risk associated with the design is as low as is reasonably practicable. In those situations, a measure for a safety scheme's benefit relative to its cost is required, as more efficient safety schemes should be preferred over less efficient ones to maximize the number of lives saved under societal resource constraints. To this end, the J-value has been introduced in other engineering fields as a decision support indicator for assessing the efficacy of safety features. The J-value has been derived from societal welfare considerations (the Life Quality Index) and is adopted in the current paper for applications in fire safety engineering. It is demonstrated herein how the J-value can inform decisions on fire safety, and how it can provide a basis for assessing whether or not a proposed fire safety scheme should be implemented. Future work will focus on its implementation as a tool for assessing the benefit of real life fire safety scheme implementations, such as sprinkler installations.