當「性能方法」（Performance-based method）於評估火災發性時建築材料和各項消防系統已變得更為廣泛和有效時，建立一套客觀的標準（objective criteria）來判斷火災的各項行為也同時變得的分的重要。然而「閃燃」的發生，可說是建築物防火整體安全評估中最具代表性的一項臨界條件。本文中，包含各學者定義的閃燃發生的實驗數據，以及一般最常見閃燃發生起始點（onset of flashover）的預測方程式。此外，文中也以利用一些相關室內火災發生閃燃的方程式，計算出一些閃燃發生的數值結果。

While the use of performance-based method for evaluating the behaviors of materials and fire protection systems becomes more widespread and effective, setting an objective criterion to judge fire behaviors becomes more and more important. However, flashover is reasonably assumed the best representation of critical conditions when the fire safety evaluation of buildings is considered. The experimental basis for working definitions of flashover and the equations for predicting the most common of the onset of flashover derived by the experts are presented. In addition, some of the numerical results deriving from the relative equations for the compartment fire that can be used to estimate flashover are presented.