Although models of subcooled flow boiling at high pressure have been studied extensively, there are few equivalent studies for numerical modelling at low pressure. Recent experimental and numerical studies on subcooled boiling flow at low pressure have indicated that empirical models developed, and verified, for high-pressure situations are not valid at low pressures. A study has been conducted to extend a two-fluid model, previously used for predicting subcooled boiling flow at high pressures into being applicable for low-pressure conditions. This study demonstrates that the following closure relationships or parameters are important for an accurate prediction of void fraction distributions at low pressures: (i) partition of the wall heat flux; (ii) bubble size distribution and interfacial area concentration; and (iii) bubble departure diameter and its relationship with bubble frequency. Different existing correlations for all these are tested and some new correlations are proposed. Predictions of the proposed model agree closely with a number of published experimental data.