Organizational and technological support for improving the energy efficiency of repair and construction works in the housing industry

. Presently, due to the growing shortage of basic energy resources, the increase in the cost of their production and the presence of acute issues associated with environmental degradation, the integrated use of energy-saving measures and innovative energy-efficient technologies in the housing and utility industry is one of the necessary conditions for the successful development of the country's national economy and maintaining a favorable state of the environment. The use of modern energy-efficient materials and technologies in residential buildings, including during the overhaul of residential buildings, makes it possible to reduce energy consumption and save significant funds for citizens on utility bills.


Introduction
Providing population with a sufficient amount of natural resources in the modern world is the main condition for the preservation of life and the development of civilization [1].The issue of depletion of limited reserves of natural resources causes an urgent need to develop programs for energy saving and improvement of energy efficiency of capital construction projects, including civil buildings [2].
Energy saving is a set of technical, organizational, technological, legal, scientific, industrial and economic measures aimed at the most efficient and rational consumption of fuel and energy resources, as well as the use of renewable energy sources [3,4].

Research materials and methods
The development of the housing and utility industry of the national economy is associated with the use of thermal energy, which is generated through the use of fuel and energy resources.The mass consumption of energy in production leads to the rapid depletion of natural resources, therefore, there is a need to implement the focus on rational energy consumption and efficient use of energy resources in the sectors of the Russian economy through the development of a system of legal, technical, economic and organizational measures [5].
According to the State Report on the State of Energy Saving and Increasing Energy Efficiency in the Russian Federation, as of 2021 there were 871,932 operated residential buildings in the country, including 7.1% with a reduced energy efficiency class (E, F, G) and 86.5 % with an indefinite energy efficiency class [6].Therewith, the share of operated apartment buildings with the highest, high and increased energy efficiency class assigned amounted to 6.4% (0.3 more than in 2020).
The distribution of apartment buildings commissioned in 2021 in terms of the energy efficiency class is shown in Fig. 1.Fig. 2 shows that in 2021 the share of apartment buildings equipped with individual heating plants (ITPs) increased compared to the previous year.In absolute terms, the number of apartment buildings equipped with ITPs increased from 173.3 thousand units to 197.2 thousand units.Thus, there is an obvious growth in equipping civil buildings with modern and efficient technologies, the use of which can significantly reduce the energy intensity of facilities.The state of equipment of apartment buildings with communal metering devices and apartments in apartment buildings with individual metering devices in Russia in 2021 is shown in Fig. 3 and Fig. 4.  A significant effect in saving energy resources in the housing and utility industry is achieved through the introduction of energy efficient technologies, both in the direct construction of buildings with high energy efficiency classes, and in the reconstruction and overhaul of the existing housing fund [7].Modern measures used to reduce energy intensity include the implementation of thermal insulation for building envelopes, the installation of metering devices (communal and individual), the installation of an ITP with automatic control of the temperature of the heating medium, the use of remote automated collection of meter readings, pipe insulation, installation of roof anti-icing systems, etc. [8,9].Other areas of rational and energy efficient use of natural resources should also be taken into account, including the use of alternative energy systems [10].

Results and discussion
Energy and resource saving are important tasks in the modern world.The level and quality of life of citizens of any state depends on the success of their resolution, therefore energy conservation is a priority for the leading countries of the world, including in the construction industry and in the development of the housing and utility complex.Improving the energy efficiency of capital construction projects by building them independently of external energy sources, as well as performing energy-efficient reconstruction of facilities, is becoming a key area of energy saving.
The use of energy-saving equipment allows to reduce the cost of electricity, heating and ventilation of the building through the use of alternative energy sources and innovative technologies [11].The availability of technologies for extracting energy from renewable sources makes it possible to build energy-independent buildings with an environmentally friendly infrastructure.In order to reduce heat loss, building envelopes must not only meet the requirements of strength, stability, fire resistance and durability, but also have adequate thermal performance [12].
In order to increase efficiency, the use of energy-saving technologies in the housing and utility industry should be predominantly of complex nature, therefore, when implementing repair and construction projects, several options for measures should be considered and evaluated for implementation, after which the most effective one can be selected.
Energy efficient measures are aimed at reducing the cost of energy consumption, reducing unproductive losses, rational use of resources and quality service delivery [13].Optimization of the level of resource consumption is a process of limiting their excessive consumption, for example, through the use of pressure pumps with a variable nozzle diameter, the installation of heat exchangers, as well as systems that allow to automatically adjust the parameters of the heating medium in the heating system with the account of ambient temperature.The installation of a two-stage heat consumption control system is also a modern and effective way of saving energy, which allows to reduce heat losses in a building by up to 20 -25%.In this case, the first stage is taking into account the overall heat balance of the building (automation of heat input units using electronic controllers for the heating system).At the second stage, the individual control of heaters is carried out by installation of thermostats.The implementation of measures to account for and control the use of resources creates the conditions for determining irrational losses and the subsequent formation of organizational and technological measures for their minimization or complete elimination [14].
Measures aimed at reducing irrational losses make it possible to achieve sufficiently high energy efficiency indicators during the operation of capital construction facilities.The insulation and sealing of the building envelope (insulation of external walls and roofs, basement insulation, installation of energy-efficient window systems) is worth emphasizing among such measures.A set of measures for the insulation of walls and roofs not only reduces heat losses in a building, but also prevents the structures from freezing, prevents the formation of mold and prolongs the service life of structural elements.
Modern high-quality glazing, which ensures low heat transfer through window openings (reduction of heat loss by 10-15%), is used to achieve low energy consumption standards in buildings.Energy saving measures also include thermal insulation of heating pipes in unheated premises.
At the present stage, energy saving measures related to the use of alternative energy sources have become increasingly popular and developed, which is largely due to their environmental friendliness and availability.
An analysis of costs of implementing a set of energy efficient measures allows us to establish that the necessary financial investments may vary [15].The implementation of energy efficient solutions in some cases requires little cost, while in others it requires a large amount of investment, thereby significantly increasing the cost of repair and construction work.This causes the need to solve the organizational and technological problem of optimizing the choice of energy efficient measures in the housing and utility industry.The set of energy and resource saving technologies used to improve the energy efficiency of buildings should not only be environmentally friendly and safe, but also accessible to the public.

Conclusion
The direction of energy saving and energy efficiency is given considerable attention by the state in Russia.The legal and regulatory framework in this area contributes to the successful achievement of energy saving goals, and therefore it is important to regularly update the legal framework in this area.
In order to ensure intensive development of the country's economy and improvement of the level and quality of life of the population, it is important to adopt appropriate measures to improve the technical condition and functional and consumer qualities of residential and public buildings, thus repair and construction work is carried out using energy efficient technologies and materials.
Overhaul and reconstruction of the housing fund using energy efficient materials and technologies can significantly reduce energy consumption in buildings.The residential sector has significant potential for energy efficiency improvements.Improper technical condition of engineering systems, facades, roofs of buildings can lead to significant heat losses.
The introduction of energy saving technologies in order to reduce the energy intensity of public buildings is relevant due to the significant cost of energy resources and the growth of tariffs for housing and utility services.At the same time, one can observe the presence of certain factors that limit the use of energy saving technologies, among which one should single out the low awareness of the population about the possibilities of introducing energy saving technologies during the overhaul of buildings, the rather high wear and tear of buildings in operation, the lack of interest among the heads of organizations and property owners in saving energy.However, the use of such technologies during the overhaul of buildings significantly reduces the cost of energy resources.
In the past, the use of building materials with low energy efficiency indicators led to the emergence of a large number of residential buildings with low values of heat transfer resistance of building envelopes, and the lack of devices and metering units for the consumption of thermal energy, hot and cold water, gas, electricity led to their irrational consumption.Heat losses in old housing fund can be 20-30% higher than in modern residential buildings.
The greatest level of heat consumption occurs in the heating and hot water supply systems of old houses, built in the middle of the 20th century.In addition, significant heat losses in buildings occur through the external enclosing structures of walls, windows and through ventilation in the absence of an air recovery system.
The following are the main defects in the building envelopes that contribute to an increase in heat loss of buildings: • loss of bricks from window and door lintels; • erosion of seams in brickwork; • destruction or delamination of the plaster layer of walls; • stratification of brickwork; • weathering of wall material; • formation of cracks in the walls.These facade defects contribute to a decrease in the value of heat transfer resistance of wall enclosing structures and increase heat loss.
The current state of the internal engineering systems of most residential buildings today is also in poor condition.Deep corrosion of the mains of water supply systems and poorquality thermal insulation of pipes are the main reasons for the overspending of utility resources, namely: • with deep corrosion of cold-water supply pipes, there is a high probability of formation of fistulas, through which, in case of untimely repair of emergency sections of pipes, can occur water leaks, which leads to overspending of resources; • poor-quality thermal insulation of pipes of the heat supply and hot water supply system leads to heating of the basement or attic premises of houses, which contributes to a significant increase in the consumption of thermal energy.
The urgency of measures to improve the energy efficiency of residential buildings and housing and utility services is determined by the goal of increasing the energy efficiency of the economy in Russia.Considering that the total consumption of energy resources in the country in 2021 amounted to 888.7 million toe, where 10.3% is occupied by the agriculture, service and utility industries, it can be determined that the introduction of energy saving technologies upon overhaul is of tremendous importance for the domestic economy.The use of modern energy efficient measures and modern engineering solutions in residential buildings contributes to a significant reduction in energy consumption.

Fig. 1 .
Fig. 1.Distribution of commissioned apartment buildings in Russia in terms of their energy efficiency class [6].

Fig. 2 .
Fig. 2. Share of apartment buildings in Russia equipped with individual heating plants compared to the total number of buildings [6].

Fig. 3 .
Fig. 3.The state of equipment of apartment buildings with communal metering devices [6].

Fig. 4 .
Fig. 4. The state of equipment of apartments in apartment buildings with individual metering devices [6].