Off-site construction can represent a potential solution for worldwide mass housing demand and has gained a lot of attention during the refugee crisis in Europe. In particular, modular construction is one of the most cost-effective off-site methods for various types of buildings. Its characteristics are cost-effectiveness, quality control and quick on-site assembly. The design challenge is to join the stated advantages with operational sustainability, which is susceptible to climate-determined and energy efficient design. Therefore, the purpose of this paper was to systematically evaluate energy and visual (daylight) efficiency of singular prefabricated modular unit. In order to emphasise the relevance of local climate, modular unit model was analysed at five different locations, monitoring cooling, heating and lighting energy use. Results showed similarities and differences between the analysed locations and implemented design measures. The conducted analysis included variation of orientation, window to wall ratio, window distribution, envelope thermal transmittance and glazing characteristics. Surprisingly, the results indicate substantial impact of artificial lighting on the total energy use. Therefore, emphasising a direct connection to the Spatial Daylight Autonomy (sDA) values of the modular units. With sDA values below 50%, lighting can represent up to half of the total energy use. (C) 2018 Elsevier Ltd. All rights reserved.