The effect of urban microdistrict structure on the external heat transfer and heat consumption in similar-type buildings

Abstract

The article deals with conjugate heat transfer between a building and the environment, the parameters of which (temperature and velocity) are determined by the features of the urban environment. The subject of the study includes two similar-type buildings located in two different microdistricts of Moscow having different density and structure of the urban environment. The heat consumption in buildings according to the regulations that are currently in force and according to those that were valid at the time the buildings were constructed is briefly reviewed. It is shown that heat losses through the external enclosing structures calculated according to the current regulations, as well as the costs for heating (in money terms) of the premise in the building's corner may be a factor of 1.5-2 higher than those for premises located in the building's central part. Results from mathematical modeling of external heat transfer in similar-type buildings in different districts of Moscow taking into account the nearby buildings and structures are presented. The fields of wind velocity and the distributions of temperature and external heat transfer coefficient over the outer surfaces of buildings are obtained. It is shown that the highest nonuniformity in the distribution of temperature and heat transfer coefficient over the building outer surfaces is observed in the horizontal direction. This means that different amounts of heat will be required in order to maintain comfortable conditions in the premises located at the same floor of a building. Thus, the cost of living in apartments is determined not only by the cost of thermal energy, but also by the topology of urban environment. It is pointed out that, by monitoring the heat consumption in each individual apartment in a building, it is possible to identify the difference in payment for heating the same premises, the outer walls of which are subjected to different effects of the environment formed by the urban surroundings. Means required to maintain comfortable conditions for different premises in two buildings of a similar design but located in different conditions of urban neighborhood are evaluated. It is noted that, according to the results obtained within the framework of the performed study, the influence of urban environment on the heat consumption in a building is on the whole rather insignificant; nonetheless, its local effect on the heat consumption in individual premises within the considered buildings is observed. Thus, the difference between the amounts of heat consumed by premises located in the corners of buildings located in different districts of Moscow can reach 15 — 18%, and for central premises located at the same floors of the considered buildings this difference makes 10 — 12%.