Abstract. The paper deals with the causes and consequences of malfunctioning of natural and mechanical ventilation systems in civil buildings of Russia. Furthermore it gives their classification and analysis based on the literature review. On the basis of the analysis technical solutions for improving the efficiency of ventilation systems in civil buildings are summarized and the field of their application is specified. Among the offered technical solutions the use of autonomous ventilation systems with heat recovery is highlighted as one of the most promising and understudied. Besides it has a wide range of applications. The paper reviews and analyzes the main Russian and foreign designs of ventilation systems with heat recovery that are mostly used in practice. Three types of such systems: UVRK-50, Prana-150, ТеFо are chosen for consideration. The sequence of field tests of selected autonomous ventilation systems have been carried out in order to determine the actual air exchange and efficiency of heat recovery. The paper presents the processed results of the research on the basis of which advantages and disadvantages of the tested ventilation systems are identified and recommendations for engineering and manufacturing of new design models of autonomous ventilation systems with heat recovery are formulated.

Full-scale tests of recuperative heat exchangers of autonomous ventilation units of a new design were carried out in order to determine the efficiency of heat recovery in them. As a result of the tests, it was found that the efficiency of heat recovery in such recuperative heat exchangers varies from 40 to 70 %, depending on the initial parameters of the supply and exhaust air. It was also found that in order to achieve the same heat recovery effect, it is advisable to use the construction of heat exchangers with corrugated mesh than the construction with corrugated plates because the first construction with a comparable heat recovery effect provides up to one and a half times lower aerodynamic drag. During the tests was also made an approbation of a new protection scheme for recuperative heat exchangers against freezing.

The article describes an approximate analytical method for calculating the moisture regime of multilayer building envelope structures. The novelty of the proposed method lies in the use an analytical dependence for determination the position of the flatness possible condensation, obtained as a result of studying the function which is the difference between the partial pressures of water vapor in the considered section the enclosing structure and the partial pressure of saturated water vapor at the extremum. The article presents the results of calculating the moisture regime of the outer wall of a residential building under construction in Samara using monolithic sandless expanded clay blocks with a density equal to 600 kg/m3. The calculation showed that during the heating period the coordinate of flatness of possible condensation in sandless expanded clay concrete, measured from the inner surface of the wall moves from 0.444 m to 0.5 m. The made assessment of moisture accumulation in the considered outer wall, both for the annual period of operation of the building, and for the period of months with negative temperatures, showed compliance with the regulatory requirements for heated rooms.

This article discusses the issue of determining the value the average wall temperature of the plate of a recuperative heat exchanger type “air-to-air” with a corrugated mesh insert based on the results processing the data of a physical experiment to determine the thermohydraulic characteristics such heat exchange surfaces. It has been established that the temperature fi eld of heat exchange surfaces of this type is nonuniform, depends on the conditions of heat exchange and hydraulic regimes of air fl ow. Therefore, the adoption of the arithmetic means value of the measured surface temperatures as the calculated average temperature of the heat exchanger wall entails signifi cant errors in the subsequent processing of experimental data and fi nal the values of the heat transfer coeffi cients, the values the Nusselt criterion and the criterion equations of heat transfer. It is proposed to determine the average value the wall temperature of the heat exchanger based on the results of measurements the wall’s temperatures, the estimate of the coordinates the center of distribution the results of measurements the wall temperatures, the equations of heat balance and heat transfer.

This article presents the results of a theoretical study of the infl uence the outside air infi ltration through the enclosing structures of the walls on the amount the air’s exchange in low-rise residential buildings. Based on the information analysis from offi cial documents of state statistical and analytical bodies, the most frequently used external wall structures in modern low-rise residential construction have been determined. Based on the provisions analysis of modern regulatory documents in the construction’s fi eld, the minimum values the required air exchange were determined and the calculations of the values the infi ltration air fl ow through the outer walls for various premises of low-rise residential buildings were made. Based on the results of the analysis and calculations was made a generalizing conclusion that for the considered premises of modern low-rise residential buildings, at the expense of the infi ltration of outside air through the enclosing structures of the walls, it is impossible to provide even 20 % of the minimum air exchange.