Passive solar heat supply systems, despite relatively low additional capital investments compared to active solar installations, have not become widespread, unlike the latter. However, the design of external fences having the function of solar radiation utilization makes it possible to achieve high energy efficiency in the building operation. The current situation is partly due to the lack of technologies for prefabricated energy-active building structures and calculation methods that justify the thermal engineering parameters of their execution for the actual irradiation of construction areas. The paper presents a developed engineering calculation algorithm that can be applied both to massive outdoor fences and lightweight ones made of modified sandwich panels. A constructive design of external solar-absorbing facing metal sheets of sandwich panels in the form of channels connected to the internal environment of the premises by means of overflow pipes with air valves and having a translucent fence to protect against environmental influences is proposed. The results of calculations using the developed methodology for the climatic conditions of the Voronezh Oblast showed that the change in the size of the cross-section of the channels with natural air circulation does not have a significant effect on the heat collection. But despite the received justification, they should not be performed with a width of less than 0.05 m and more than 0.1 mm. To achieve high rates of substitution of traditional resources in consumption by buildings, it is necessary to increase the length of energy-active structures in external fences.