**Abstract**

Building-integrated photovoltaic (BIPV) replaces building envelope materials and provides electric power generator, which has aroused great interest for those in the fields of energy conservation and building design. Double-skin façade (DSF) has attracted significant attention over the last three decades due to its bi-layer structure, which improves thermal and acoustic insulation and therefore increases the energy efficiency and thermal comfort of buildings. It is hypothesised that the integration of BIPV and DSF (BIPV-DSF) would help buildings in reducing energy consumption and improving indoor thermal comfort concurrently. However, the prototype of the BIPV-DSF has not been well explored. Thus, the investigations of the BIPV-DSF are worthwhile. Numerical simulation is a cost and time effective measure for the design and analysis of buildings. This chapter spells out a comprehensive method of numerical simulation modelling of the novel BIPV-DSF system in buildings, which is carried out by using a graphically based design tool – TRNSYS and its plugins. TRNSYS has been validated and widely used in both the BIPV and building related research activities, which are capable in analysing the effects of BIPV-DSF on building performance such as energy consumption and indoor thermal condition.

**Keywords:** numerical simulation modelling, TRNSYS, TRNFlow, double-skin facades (DSF), building-integrated photovoltaic (BIPV)
