Improving the energy efficiency of residential and civil construction largely depends on how much fossil fuel we spend on heating, cooling, electric lighting, and other human needs during the operation of the building. The results of calculations of energy savings that can be provided by a passive system of using solar energy for these purposes, which, unlike active systems such as photovoltaic batteries or solar collectors for heating and hot solar water supply, does not require engineering equipment maintenance and is an element of the building itself, is part of its space-planning and a constructive solution. From the point of view of capital expenditures on its device, it is attractive. This is a “solar fireplace” or a Trombe wall – the simplest of all passive systems, the effectiveness of which was used in ancient Rome. The article presents the results of the work carried out by the Department of Architectural and Construction Design and Environmental Physics (ASPiFS) within the framework of master’s and postgraduate works on the rapid justification of the feasibility of using Trombe walls already at the decision-making stage. It is noted that the use of such structures is advisable in the new southern regions of Russia. The dependence of energy savings by such systems depending on the climatic conditions of the construction site is shown.