As an inevitable result of the growing population in recent times, the requirements of housing facilities, land scarcity, and overexploitation of natural resources have created many problems. One solution for the lack of land is to have multi-storey apartment buildings. Hence, over the last few decades, the number of tall buildings has seen an exponential increase. The apartment spread over two floors, is considered upmarket due to the larger floor area. However, one factor that has been a huge obstruction to promoting duplex apartments is the higher cost. In this study, a novel concept is introduced where a proper load-bearing floor is needed only once on two floors. The duplex is double-height, using lightweight concrete panels supporting lightweight concrete floors. Recycled expanded polystyrene (REPS) based light-weight panels are used as the load-bearing walls, and the NERD slab system is introduced for the intermediate floor. The structural performance was assessed using the comparison of two finite element models for duplex and conventional concepts. It was observed that the duplex concept is structurally feasible in comparison with the conventional concept. The study emphasises that an approximately 30% dead load reduction in typical floor levels has occurred due to the lightweight beam slab system in between floors.