This paper reports on an investigation of the natural ventilation and heat gain reduction of a new façade design referred to as the Thai modern façade (TMF). Two configurations were considered namely: Thai modern façade wall (TMF) and Thai modern façade wall with fin (TMF-WF). The first (TMF) was composed of two layers which consisted of an inner layer of clear glass and an outer layer consisting of a combination of fibre cement and clear glass slats. The second configuration TMF-WF included an external layer made from aluminium fins and installed at the front of the outer layer. The space between the external fins and the outer layer can be adjusted for protection from direct sun radiation penetration into the room space. There are openings located at the bottom (room side) and the top (ambient side). The size of each opening is .084 m2/unit. The surface area of the TMF and TMF-WF is 1.284 m2. Two units of each façade were integrated into the south facing wall of rooms each of volume 17.28 m3. Experimental results showed that the TMF-WF could reduce heat gain by up to 227 W/m2. With the TMF-WF, velocity field measurements indicated that the induced airflow rate was between 0.015-0.04 m3/s and the corresponding air change varied between 3-8 ac/h. The indoor illumination level varied between 340-2000 lx. The room temperature of the TMF-WF was lower than that of the TMF by about 2-3 °C in the afternoon. Such performances are quite significant for natural ventilation since the lowering of indoor temperature reduces air conditioner energy consumption if used for cooling. Therefore the proposed configurations, especially the TMF-WF, should be recommended for residential and commercial buildings as a new design alternative for modern sustainable architecture.