Neolepenism is a new type of energy efficient architecture that could respond to the challenges of sustainable development, primarily as a passive means of protection in the fight against the effects of global warming and climate change. The author improved and optimized the positive experiences of the architecture of Lepenski Vir (Serbia) and made a model of a small family house of neolepenism with a flat roof, which he presented at the 50th International Congress and Exhibition on HVAC in Belgrade in 2019. During the presentation of the model, in the discussion at the exhibition, the question was asked: "Can this architecture be applied in climatic conditions with frequent occurrence of morning fog?" Using the meteorological databases of the Meteonorm program and the typical meteorological years for Ljubljana (Slovenia), as well as the previously developed program in Excel that was used in calculations for this architecture of neolepenism, the author presents the results for Ljubljana, a city located in the valley and where morning fogs are common. In meteorological data, the appearance of frequent morning fog is manifested through a reduced intensity of direct solar radiation in the morning. The paper presents conclusions concerning the optimal orientation of neolepenism buildings for this type of climate depending on the energy class of the building.The obtained results at the level of the whole year indicate that for the needs of heating, the eastern orientation is slightly better than the southern one for the buildings of energy class B, while for the less isolated buildings, the southern orientation has a slight advantage. For the area of Ljubljana, the orientation of the neolepenism building does not play a significant role for heating needs, but still the author believes that the originally assumed eastern orientation should be kept as optimal, due to the need for cooling during the summer season. However, in addition to good thermal insulation, the compactness of the form of neolepenism architecture also plays a crucial role in saving energy and achieving thermal comfort.