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9TECHNICAL SCIENCES
PRINCIPLED APPROACHES TO OPTIMIZATION OF SOLUTIONS FOR THERMOMODERNIZATION OF BUILDINGS
MaKsymov A.
Head of the department of energy saving and thermomodernization in construction of Research Institute of
Construction Production, Kyiv ORCID: 0000-0001-7029-5690 Halinskyi O.
Doctor of Technical Sciences
Professor of the Department of Construction Organization and Management, Kyiv National University of
Construction and Architecture, Kyiv ORCID: 0000-0003-3648-4572
Abstract
Analysis of the most widespread constructive-technological solutions used in thermomodernization, showed the impossibility of choosing the optimal solution for a single enclosing structure only by direct assessment of physical, mechanical and technical and economic characteristics.
It is proposed to select the optimal constructive-technological solution in thermomodernization projects from all possible in two stages. At the first stage, it is necessary to discard those solutions, the implementation of which for this type of building is technically impossible or economically or technically impractical. In the second - to assess the system of indicators that comprehensively characterize the constructive-technological solution.
In the article, based on the analysis of literature sources and the authors' own experience in the development and maintenance of thermomodernization projects, a system of criterion evaluation for constructive-technological solutions of thermomodernization is developed. The optimal technical solution is the solution that received the highest score on the total.
This method is based on a pairwise comparison of options depending on the annual savings of thermal energy from the cost of thermomodernization measures, allowed to determine the most technically, energy and cost-effective options for complex thermomodernization.
Keywords: thermomodernization, optimal constructive-technological solution, estimation of technical solutions of thermomodernization, optimal set of constructive-technological solutions
Introduction. Improving the energy efficiency of construction projects, new and already built, is becoming a strategic direction of the country's economy.
Today, many scientists solve problems on the development and implementation of technical, organizational and technological solutions for the implementation of projects to improve energy efficiency in various sectors of the economy, these tasks are today one of the most pressing.
The decision on the choice of technical solutions for thermomodernization should be based on their comprehensive assessment, for which an appropriate system of criteria should be formed.
Analysis of research and publications. Analysis of the literature has shown that different approaches can be applied to the assessment of thermo insulation systems.
Thus, the provisions of Ukrainian normative documents set minimum requirements for thermo performance of thermo insulation structures of buildings and energy performance of buildings or their separate parts, which are determined on the basis of economically justified level of energy efficiency of the building taking into account its expected life cycle. human needs and the creation of optimal microclimatic conditions for his stay and / or living in the premises of such a building.
The document states that technical solutions to ensure the optimal level of energy consumption costs and
further improve the energy efficiency of buildings should take into account climatic and local characteristics, indoor climate and economic efficiency. Such measures should not conflict with essential requirements for buildings, such as ease of access, security and purpose of the building.
Materials and structures used for thermo insulation of buildings must not contain and emit substances that are toxic and harmful to human health.
Ukrainian normative documents also set the minimum allowable value of heat transfer resistance of opaque enclosing structures, translucent enclosing structures and doors of residential and public buildings.
The authors [7] compare the design solutions of energy-efficient enclosing wall structures on the following indicators: wall thickness, heat transfer resistance, weight of 1 m2 of wall, cost of 1 m2 of wall, complexity of construction of walls, usable area of interiors.
The authors [8] distributed the factors influencing organizational and economic decisions when choosing materials for thermo renovation of buildings by the following groups:
1. Economic: cost of material, cost of work, complexity of work, durability, operating costs.
2. Environmental: fire resistance, chemical resistance, biological resistance harmful
3. Thermophysical: thermo conductivity, density, vapor permeability, hygroscopicity, frost resistance, compressive strength, sound absorption;
4. Esthetic: brightness, color, tone, texture, color.
The authors [10] consider the criteria for the customer to choose a thermo insulation system from a slightly different position, taking into account the organizational aspect:
1. The presence of successfully installed and operated thermo insulation systems in houses of similar class.
2. Completeness of the system taking into account the correctly specified costs of materials per unit area.
3. Availability of technical documentation for the system, album of technical solutions for the connection of the system to the elements of the facade, detailed installation instructions.
4. Prices per square meter of the facade surface, taking into account the complete set of the system.
5. Terms and conditions of deliveries of the materials which are a part of a set of system (the schedule of deliveries).
6. Own weight of the proposed system (this item is especially important for high-rise buildings).
7. Providing the supplier with a choice of textures and types of plasters, as well as their tinting in volume.
8. Engineering maintenance (training, chief installation, technical supervision).
9. Issuance of guarantees for the system for at least 5-10 years.
The author [11] identifies and substantiates the following criteria for evaluating external insulation systems:
1) Reliability and stability of the insulation system.
2) Fire protection.
3) Thermo protection.
4) Heat resistance.
5) Sound insulation.
6) Diffusion and condensation of water vapor.
7) Corrosion protection and chemical resistance.
8) Durability.
9) Maintainability.
10) Comfortable living conditions.
11) Color and architectural solutions.
Setting objectives. Develop criteria and evaluation system for the selection of optimal constructive-technological solutions for thermomodernization for individual enclosing structures.
Research methods. Methods of analysis and synthesis, historical, were used to study the goal set in the work; statistical, retrospective analysis, analytical grouping; method of mathematical modeling, expert evaluations, successive iterations.
Main part. Evaluation and selection of optimal design solutions should be carried out in several stages. At the first stage, the analysis of thermo insulation systems of enclosing structures (facades, roofs, windows, ceilings over the unheated basement) presented on the market of Ukraine and Europe is carried out and those that are:
- it is technically impossible to apply at thermo modernization of school buildings;
- have significant shortcomings from a technical point of view;
- in terms of their cost and the cost of installation are several times more expensive than other systems with the same technical characteristics.
In order to select the optimal technical solutions for thermo modernization, a more thorough comparative analysis should be performed on the rest of the systems.
According to the analysis of literature sources, each thermo insulation system can be evaluated by a number of indicators that characterize its various properties, which depend on the composition of the system - thermo insulation material, its equipment and additional insulation materials (waterproofing, vapor barrier, etc.).
The decision on the choice of technical solutions for thermo modernization should be based on their comprehensive assessment, for which an appropriate system of criteria should be formed.
Taking into account the analyzed approaches to the assessment of insulation systems of enclosing structures, regulatory requirements and our own experience in developing projects of thermo modernization of buildings, inspection of technical condition of existing buildings, etc. we have developed our own system of assessment and selection of technical solutions for thermo modernization.
There is no doubt that for all insulation systems the most important thing is to ensure a given level of heat transfer resistance. Therefore, when creating an evaluation system, we proceeded from the fact that all technical solutions for thermo modernization of one structural element, which are compared, provide the same, specified by standards, the level of heat transfer resistance.
As a result, we have the following list of criteria:
1. The density of the insulation
2. Thermo homogeneity
3. Diffusion and condensation of water vapor
3.1. Hygroscopicity
3.2. Vapor permeability
4. Influence of groundwater
5. Environmental friendliness
5.1. Fire resistance
5.2.Chemical resistance
5.3.Biological stability
5.4. Harm
6. Reliability and stability
6.1. Influence of own weight of system
6.2. Influence of hydrothermo loads due to daily and seasonal fluctuations of temperature and humidity
6.3. Influence of deformation at shrinkage
6.4. Impact strength
6.5. Influence of wind pressure and wind suction
6.6.Effect of solar radiation
7. Maintainability
8. Seasonality of work
9. Ensuring high quality of work due to the manu-facturability of the system
9.1. Possibility of interchangeability of the elements used in system of warming
9.2. The need to prepare the surface for mounting the system
9.3. The amount of additional costs for the implementation of an individual project
9.4. The complexity of the work
9.5. Qualification of performers is required
9.6. The number of sizes of products used in the system
9.7. Number of technological processes
10. Economic (economic efficiency)
10.1. The cost of installing 100 m2 of the system
10.2. The cost of operating the system for 25 years (per 100m2)
10.3. The degree of increase in the heat transfer resistance of the structure under the condition of increasing the thickness of the layer of insulating material, and hence its cost by 10%.
11. Sound insulation
12. Thermo conductivity of the heat insulating layer
13. Esthetic
In the second stage, the assessment of design and technological solutions using the above list of criteria. A system of criterion evaluation has been developed, which ensures the comparability of decisions, to include both objective indicators and those determined by the person conducting the evaluation, based on their own experience and common sense.
Our system of evaluation of technical solutions for thermomodernization assumes that the evaluation by criteria that have sub-criteria is defined as the sum of evaluations of sub-criteria [12]. Each sub-criterion is evaluated by experts in points from 0 to 5, where 0 is the worst value of the indicator, 5 is the best. Criteria that do not have sub-criteria are also evaluated on a five-point scale.
The total indicator of evaluation of technical solutions (Co) is defined as the sum of evaluations for each of the criteria (Ki), taking into account the relevant weights (ai, si), taking into account the importance of each criterion or sub-criterion (ki).
The weights of the criteria for the assessment of different types of enclosing structures were determined by experts. Moreover, the more important criteria have a higher weight, and less important - lower, and the sum of all weights should be one. Thus, the importance of the criterion and its evaluation is taken into account.
Accordingly, the optimal technical solution is the solution that received the highest score on the total.
As a result of application of such technique the basic constructive-technological decisions for thermal modernization of each separately enclosing design of the building can be defined.
The list of constructive-technological solutions to improve the energy efficiency of the facility as a whole is formed based on a given "baseline energy efficiency" - the maximum possible level of heat loss by the house, set by building codes, which is achieved by implementing various combinations of energy saving measures. replacement of windows, modernization of engineering
systems) using different structures and equipment with different technical and economic characteristics. Here is a large array of solutions that determine:
- the relative cost of construction work;
- the level of thermal energy savings that can be achieved.
As a result, there is a problem of choosing the optimal combination of constructive-technological solutions - which at the lowest cost will provide greater savings in thermal energy.
The method of optimizing a set of constructive-technological solutions for thermomodernization of the building as a whole consists of the following stages:
1. The constructive-technological solutions which can be applied to each enclosing design are defined;
2. Possible variants of modification of each constructive-technological solutions on heat transfer resistance which can be as a result provided for a design are defined. This modification can be achieved, for example, by changing the thickness of the insulation.
3. The cost of application of each modification of each constructive-technological solution is defined.
4. All possible variants of a combination of the chosen variants of modifications of constructive-technological solutions are defined.
5. For each of the options are determined by specific heat losses from 1 sq.m. building area, thermal energy savings that can be achieved, the cost of a set of measures.
6. Options that do not achieve the "baseline energy efficiency" are eliminated.
7. The remaining options are evaluated simultaneously on the criteria of "thermal energy savings" and "cost of measures". To do this, all options are divided into groups, depending on the cost. In each group the option which provides the greatest economy of thermal energy is chosen. Among the selected options is finally chosen the option that, depending on the goal of optimization:
a. provides the greatest savings in thermal energy (however, it is the most expensive);
b. provides the lowest cost of activities (in the case of a limited budget);
c. at the set level of the budget provides the greatest economy of thermal energy;
d. has the lowest value of the indicator "cost of saving 1 Gcal of thermal energy".
The author breaks down the calculation program based on Excel to evaluate and select the optimal design and technological solutions and optimize the set of solutions for thermal modernization of the building as a whole.
Conclusions. Our system of criterion evaluation for structural and technological solutions of thermo modernization contains a number of indicators that take into account the physicochemical properties of insulation, environmental friendliness, reliability and stability of the insulation system, technological factors such as maintainability, seasonality, high quality of work due to system manufacturability, ability to sound insulation, efficiency, artistic efficiency. This evaluation
system allows you to comprehensively evaluate the design and technological solution and choose the best.
The method of estimating of the set of technical for thermomodernizate the building as a whole is developed. This method is allowed to determine the most technically, energy and cost-effective options for complex thermomodernization.
REFERENCES:
1. Law of Ukraine "On Energy Efficiency of Buildings" of 22.06.2017 No. 2118-VIII. URL: https://zakon.rada.gov.ua/laws/show/2118-19.
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USING THE FOURIER TRANSFORM OF THE HALF-CYCLE TO ENHANCE THE APPLICATION
OF THE PMU
Revyakin V.
Master degree Klimova T.
Candidate of Sciences in Technology, Associate Professor University «MPEI», Department "Relay protection and automation of power supply systems", Moscow,
Russia
Abstract
In this report it is offered modified discrete Fourier transform giving fast (observation window 10 ms), precise and simple for realization the algorithm of receiving estimations of parameters of sinusoidal oscillation, according to the IEEE Standard C37.118 requirements.
Keywords: PMU complexes in distributed power systems, PMU algorithms, the discrete Fourier transform, FCDFT, HCDFT, SDFT, noise and measurement errors. The possibility of using the algorithm in power distribution systems in special implementations of PMU(microPMU), requiring fast estimation at the presence of noise, is analyzed. In this article there are results of modeling various situations.
INTRODUCTION
Historically, power distribution systems did not require elaborate monitoring schemes. With radial topology and one-way power flow, it was only necessary to evaluate peak loads or fault currents, rather than continually observe the operating state. But the growth of distributed energy resources, such as renewable generation, electric vehicles, and demand response programs, introduces more short-term and unpredicted
fluctuations and disturbances [1]. This demands the need for more accurate and quicker measurements, judging from increasing changeability and uncertainty and the presence of a higher level of narrowband and broadband interference and measurement noises.
In order to expand the possibilities of using PMU devices, firstly it needs to perfect the technologies of PMU devices. For improving the characteristics of
