Renovation of five-storey residential buildings of the first mass series in the regions of Russia. Problems and solutions

The paper examines the problem associated with the reconstruction of residential buildings and the renovation of the territory of residential development of the first mass series. The issues of the current state of the five-storey housing stock in the regions of Russia are highlighted. On the example of the city of Volgograd, an architectural and spatial assessment of the development of residential development of the city is given. Attention is focused on the issues of building blocks and neighborhoods with five-story houses of the first standard series. The socio-economic, architectural and planning parameters of residential sections and apartments are analyzed in detail. Structural and planning deficiencies affecting the level of comfort of the housing stock are identified. During the discussion, the search for possible solutions related to the renovation and improvement of a five-storey residential development is shown. The evaluation of the operational qualities of the experimental construction allowed determining the complex methodological basis of possible reconstructive measures, combined in three main technological directions: renovation of the territory of a five-storey housing stock by demolishing individual buildings or entire blocks; renovation, which is based on major repairs of the housing stock without interfering with the architectural and structural system of a five-stored building; renovation aimed at changing the architectural and planning structure of residential buildings by adding additional volumes. The ways of implementation of technological directions of reconstruction of five-storey buildings that increase their compliance with the requirements of sustainability are considered.


Introduction
Before investigating the problem associated with the reconstruction of residential buildings and the renovation of the territory of residential buildings of the first mass series, we would like to take a closer look at the socio-economic and architectural and planning features of the development of residential buildings in cities and towns. It is necessary to answer the main question -residential buildings of this typological group are able to meet modern requirements or not. On the one hand, five-storey buildings, today have a high obsolescence, and for some series of standard houses and physical deterioration. On the other hand, the state of engineering structures with a careful attitude to their physical condition could meet the requirements for their safe use for many years to come. In this situation, there is a need for close attention to issues related to solving this important problem for the state's economy.  The results of numerous studies show that the demolition of old buildings built according to standard projects and the construction of new multi-storey residential complexes in their place are not justified from an economic point of view, as the cost of dismantling one building is approximately 40% of the total cost of building the frame of a new building [10]. Already in the mid-1970s, it was recognized that the real cost of building and living in a multi-storey dwelling will increase in proportion to the increase in the number of floors, so in 16-storey buildings, the housing stock will be 9-18% more expensive than in 9-storey ones. [11].
From an environmental point of view, the demolition of buildings is also not the best option. Emissions of harmful substances into the atmosphere, noise pollution, and a high level of permissible vibration from the operation of heavy construction equipment may exceed the maximum permissible standards. An important negative aspect, which clearly does not reduce the cost of new construction, is not an easy task of recycling construction debris [10].
It is still too early to talk about the social aspect of renovation, based on an increase in the number of floors and, accordingly, the density of urban development. However, experts believe that one of the factors of the deterioration of the living conditions of Russians in the modern city is precisely the increase in the density of settlement per unit of urban territory. For example, in large cities of Russia, local regulations allow for an increase in the density of the housing stock to 25 thousand m 2 , i.e. approximately up to 1.2 thousand people per hectare. For urban planning conditions in Moscow, the density of the housing stock is not normalized at all, so in multifunctional complexes it can reach 3 thousand or more people per hectare. Thus, there is about 3 m 2 of undeveloped land per person. While, according to hygienic requirements, the population density in residential buildings should not exceed 400-500 people/ha [12].
The first negative consequences of the compaction of the development will be manifested when placing parking places for personal transport on the territory of the house. On the site of five-storey houses for 180-250 people with a courtyard area with playgrounds, lawns, fountains, flower beds and 7-8 parking spaces, houses with a height of 22 and possibly more floors will be built. Accordingly, the adjacent territory, intended for 250 people, is now intended for 1 thousand or more residents of the new high-rise building. And instead of 7-8 cars of the 1950s the same house territory should accommodate almost 80 times more cars of new residents of the house. From such new realities, all the advantages of new housing for renovation are leveled, and the quality of life becomes absolutely unacceptable for a modern person [13].
The second direction, which has become widespread in many peripheral cities of Russia, has the character of minimal interference in the functional and planning structure and architecture of residential buildings. All reconstruction activities are mainly related to maintaining the proper level of capital of buildings and their engineering systems at a safe level for living. Major repairs of the housing stock, for which a number of federal and regional funding programs have been developed today, do not provide for solving the problems associated with the obsolescence of these constructions  5 and buildings, which determine the quality of the architectural and spatial environment of a modern city.
The third direction can be considered the most promising, as it allows solving the problems of renovation of five-storey buildings in a comprehensive manner, while considering simultaneously issues of architectural and aesthetic, socio-economic and environmental nature.
The experience of foreign countries shows that the gradual degradation of mass residential development provokes the formation of depressive urban zones-slums, which are problematic social zones. Taking into account the enormous scale of the impending problem, many countries (Austria, Germany, Poland, Slovenia, France, Spain, etc.) have significantly expanded the practice of using reconstructive methods to improve the consumer qualities of the living environment [6].
One of the important conditions for reconstruction in European countries is the principles of sustainable environmental development in the formation of new settlements and the reconstruction of old ones. In a practical sense, the criteria for the compliance of objects with the requirements of sustainability have become rating evaluation systems. The most widely used three international rating systems: the American LEED, the British BREEAM and the German DGNB. In Russia, since 2010, national regulatory documents and rating systems for assessing the stability of buildings and structures have been developed. One of these standards is GOST R 54964-2012 "Conformity assessment. Environmental requirements for real estate". An important condition for the sustainability of buildings and structures proposed in these regulatory documents is to ensure the optimization of design solutions: modeling and variant analysis of the environmental stability of the property; modeling and variant analysis of the thermal and energy properties of the property; optimization of the cost of the life cycle of a real estate object [14].
An example of the implementation of standards in the foreign practice of renovation of five-storey residential buildings is the draft design developed by the authors of the paper for participation in the international competition "Designing a multi-comfort house-2017". In the terms of the competition, it was proposed to develop methods for the reconstruction of four-storey apartment buildings built in 1950-1960 in the eastern part of Madrid. The quality criteria for the proposed solutions were to be international standards for the sustainability of buildings and structures. The basis of the design development was made up of two areas of interaction between a residential building and its natural environmentthe level of formation and the level of functioning (Figure 3).
The formation of a residential building involves the use of environmental techniques for modeling the architectural form. Energy efficiency is achieved by increasing the compactness and directionality of the architectural form to the energy flows of the environmentthe sun, wind. To use the energy of the sun in the reconstruction of a four-storey residential buildings is supposed by placing photovoltaic panels on the southern slope of the roof of the built-in attic floor, as well as by installing photovoltaic panels built into the structure of the fence of the loggias of the southern facade. For efficient use of wind energy, it is proposed to attach a staircase and elevator unit to the residential building, combined with the design of a "wind-collecting" tower designed to increase the efficiency of the supply and exhaust ventilation (Figure 4).

Figure4.
General view of the development of the block after the ecological reconstruction of residential buildings. Project proposal. Figure 5. Application of systems of ecological functioning of a residential building. Energy storage and distribution scheme: 1 -air intake tower; 2 -heat pumps; 3 -photovoltaic solar panels; 4automatic control system for heat pumps.
The ecological functioning of a residential building involves the use of such a constructive and technological system of the reconstructed dwelling, in which the provision of comfortable microclimatic conditions is achieved by reducing energy consumption. This system is based on thermoregulation mechanisms aimed at preserving thermal energy and using it for self-regulation of air exchange, temperature-humidity and insolation conditions ( Figure 5).

Summary
The reconstruction of the housing stock is becoming the most important stage of the economic and social restructuring of housing policy for many regions of Russia. Comparing the various ways of implementing the program of renovation of the five-storey housing stock, we would like to emphasize that none of the applied areas of reconstruction can be considered optimal for all equally conditions for the implementation of urban planning policy. Each region should develop its own most acceptable way of renovation. It is necessary to create a national system of certification of design solutions. To create it, it is necessary to study the factors that determine the compliance of the quality of the