"Вестник МГСУ"

The current need for additional domestic accommodation has necessitated the formation of new housing types for different categories of families in terms of affordability and market requirements. In particular, the demand for apartments can be met by the renovation of Soviet pre-cast concrete residential blocks. Firstly, there is a need to quantify the growth of the elderly population and the ever-increasing desire to preserve friendly relations between the generations based on Tajik tradition. Secondly, there is a need to design special residential units intended for the resettlement of extended families, family groups and families consisting of several generations. The renovation of the old Soviet buildings will reduce not only the physical deterioration of a building by complete or partial replacement of individual structures, but will also eliminate obsolescence as a result of internal redesign and enhancement of a building. An analysis of the space-planning and structure of a residential building will establish the degree of obsolescence, as well as address the question of reconstruction as a dwelling for extended families through the partial redevelopment of apartments. Such redevelopment would increase the area of common rooms to include insulated terraces and loggias, the removal of some partitions and the conservation of existing sanitary cells. This article deals with the reconstruction of large apartment buildings based on Soviet mass-produced residential block series TTZH 1-464-AC-3, which is dwelling for extended families consisting of several generations. The article proposes 4 different options for redevelopment. These options will increase the living space of the reconstructed residential building from 25 to 35 %, and will increase the population density in all dwellings by 50 %. The intention is to improve space-planning of mass-produced residential blocks, series TTZH 1-464-AC-3, in order to match the demographic characteristics of Tajikistan for extended families and family groups.

The main object of this study is the reconstruction, renovation and modernization of the housing built in the period 1975—1985. These buildings have low energy efficiency due to the poor thermal insulation properties of the walls. These apartments do not meet the necessary requirements for year round warmth and comfort.Reconstruction is more preferable, than new-build, because of the cost saving for the land acquisition. Reconstruction is generally 1.5 times cheaper than new-build with 25—40 % reduced cost on building materials and engineering infrastructure.Increasing the width of the apartment blocks from 12 to 15 m can save 9—10 % on the consumption of thermal energy for heating and reduce the m2 construction cost by 5.5—7.0 %. In—5-9 storey high-rise buildings the savings are 3—5 %.Therefore, the width of the apartment block should preferably be between 9—12 m but could be extended to 18 m. The depth of the apartments themselves will be 5.4 — 6.0 —7.2 or 9.0 m. During the reconstruction of 5-storey residential buildings (Building Type105) in a seismic zone, an increase in the width of the block and the lateral stiffness of the building is achieved by building a new reinforced concrete (RC) frame on both sides of the building with a depth of between 2 and 6 m. This technique is especially effective in increasing the seismic resistance of the building. Self-supporting walls of cellular concrete blocks (density 600 kg/m3 and a thickness of 300 mm) are constructed on the outside of the frame, taking care to avoid cold bridges.Model studies have shown that in the conditions of hot-arid climate the thickness of the air gap in a ventilated facade does not significantly change the cooling-energy consumption of the building, and heating consumption is significantly increased. The building's energy consumption is most influenced by the volume of the air in the air gap. By increasing the ventilation rate in the air gap, the energy consumption for building heating increases and for cooling — slightly decreases. For the conditions of the northern region of Tajikistan, the recommended optimal thickness of the air gap with ventilation is 60 mm.

Solar radiation is the main source of thermal energy for almost all the processes developing in the atmosphere, hydrosphere, and biosphere. The total duration of sunshine in Tajikistan ranges from 2100 to 3170 hours per year. Solar collectors can be mounted on the roof of a house after its renovation and modernization. One square meter of surface area in Central Asia accounts for up to 1600 kW/h of solar energy gain, whilst the average gain is 1200 kW/h. Active solar thermal systems are able to collect both low- and high-temperature heat. Active systems require the use of special engineering equipment for the collection, storage, conversion and distribution of heat, while a low-grade system is based on the principle of using a flat solar collector. The collector is connected to the storage tank for storing the heated water, gas, etc. The water temperature is in the range 50-60 °C. For summer air conditioning in hot climates, absorption-based solar installations with open evaporating solution are recommended. The UltraSolar PRO system offers an opportunity to make a home independent of traditional electricity. Combining Schneider Electric power generation and innovative energy storage technology results in an independent power supply. Traditional power supply systems can be short-lived since they store energy in lead-acid batteries which have a negligible lifetime. Lead-acid batteries operate in a constant charge-discharge mode, require specific conditions for best performance and can fail suddenly. Sudden failure of lead acid batteries, especially in winter in the northern part of Tajikistan, completely disables the heating system of a building. Instead, it is recommended to use industrial lithium-ion batteries, which have a significantly longer life and reliability compared to lead-acid type. UltraSolar PRO are ideal and provide a complete package, low noise and compact lithium-ion power supply.

Comfort inside buildings is dependent on temperature, humidity and other parameters. Usually the higher the temperature and humidity, the more people feel discomfort. However, if the internal relative humidity is low, the inhabitant also feels uncomfortable as a result. Headache, eye irritation, sore throat and dry skin are the symptoms of these dry conditions. Dry air reduces natural protection from bacteria, infections, and makes people vulnerable to attacks of viruses and other micro-organisms. In addition to the problems associated with low humidity, excessively high humidity can also cause problems. The optimal level of humidity in the room contributes significantly to the comfortable environment. Chill may be perceived differently at the same temperature with different values of air humidity in the room. Comfort is determined by the ratio of room temperature to humidity. The temperature perceived inside and dependent on the moisture content, is measured by the Humidex index.European regulations define a desirable range of relative humidity and comfort. The humidity-dependent zone of comfort rests within this range. High temperatures are less tolerable in the high humidity environment. Modeling results obtained before and after the renovation and modernization of a five-story residential building (105 series) in Khujand, Tajikistan, helped to define the ideal parameters of relative humidity and comfort. The author proposes an ideal ratio of relative humidity to comfort and demonstrates that the optimum humidity and temperature values contribute significantly to the comfort of a person in the hot, dry climate of Central Asia.

Reduction of energy consumption by devices designated for cooling residential buildings in the hot and dry climate of Central Asia is a most important challenge. The author uses a large apartment building (105 series), built in the 1980ies in the city of Khujand, to study the energy consumption required to cool the building after its renovation and modernization. Basic methods of reducing energy consumption for cooling buildings in hot, dry climates were applied. According to the findings of the research performed using a model residential house, ambient solar heat gain is reduced by 65 % during the hot season lasting from April to September. To cool the building, old windows are replaced by new insulated ones having a low solar heat gain coefficient (SHGC — 0.4) and external awnings are installed to protect windows looking to the West.The typical internal room temperature of +25 °C is assumed for the thermal calculations in the summer conditions. In summer, the outside temperature exceeds 40 °C in the northern regions of Tajikistan. A typical difference between the inside and outside air temperature is 15 °C. This extensive temperature difference has a negative effect on the human body. Frequently, the human body has no time to adapt to rapid temperature changes. Aged and sick people are especially sensitive to rapid temperature changes. They are more likely to experience headaches, exacerbated hypertension, atherosclerosis and other diseases. Moderate fluctuations of the air temperature are preferable, as they reduce pressure on the body's thermoregulatory mechanisms.It is noteworthy that people who remain inside buildings are not isolated from the external environment, and they must be careful to avoid sudden temperature changes. In the European regulations aimed at warm, rather than hot summer conditions, internal residential air temperature of +25 °C is considered comfortable. On the contrary, the internal temperature in residential buildings in northern Tajikistan varies from +27 °C to +28 °C. High temperatures can cause significant discomfort in the hot and dry climate like the one in Tajikistan.It is recommended to remain indoors during the day, to keep the windows open at night, and to run air conditioners in residential buildings in summer at certain time intervals.The author proposes a method of optimization of the design temperature of residential rooms using PMV and PPD indices. Optimal air circulation through open windows at night is identified to ensure comfort in modernized residential buildings.