Heat Pump Installation Research Articles

Comparative analysis of metaheuristic optimization approaches for multisource heat pump operation

Through the use of effectively unlimited energy from the environment, contemporary heat pump installations have proven to be a highly efficient means for satisfying both heating and cooling needs. As such, they are often regarded as a key driver in the electrification process of the thermal domain. Keeping in mind the significant share of the thermal demand in building energy requirements, this aspect in particular is projected to have a great impact on the overall energy efficiency improvement of buildings and increase of demand-side flexibility. The latter point is considered crucial for improving the precarious balance against the contemporary intermittent power supply obtained from a variety of renewable sources. However, in the process of increasing their efficiency, heat pump systems are becoming significantly more complex with combinations of various different sources of energy from the ground, air and the Sun. By extension, the complexity of managing their operation has also increased and proves to be a challenge even for experienced plant operators. In order to aid in this regard, relevant literature suggests that optimization algorithms can be considered as a viable tool. This paper explores the limited extent of existing state-of-the-art approaches for hybrid heat pump control via metaheuristic optimization and broadens the subject matter with a comparative study that analyzes and benchmarks several metaheuristic approaches found in the literature on similar problems. A real-world multisource heat pump installation in Ferrara is utilized as the basis for the study.

Temperature Field Modelas a Factor to Improve a Horizontal Ground Heat Exchanger of a Heat Pump System: Review of Scientific Approaches and the Content of the Analytical Model

The article is devoted to the research of issues related to the organization of control systems for heat pump installations (HPS). HPS is used to use low-potential energy of the environment in the heat supply of buildings. HPS with horizontal ground heat exchangers (HGHE) are of great importance for improving energy efficiency. The efficiency and reliability of HPS with HGHE strongly depends on the state of the soil temperature field. A large number of scientific publications are devoted to modeling soil temperature fields forHGHEparameterdetermination; a significant part of them is devoted to the study of vertical ground heat exchangers. Scientific developments presented in foreign publications on modeling the temperature field of the HGHE location environment are focused on the use of HPS in the cold supply mode and/or in the heat supply mode under conditions of a slight decrease in temperature, which excludes soil freezing. The aim of the study was to apply the existing methods of the analytical theory of thermal conductivity to develop a soil-environment TP model for the placement of a HGHE HPS; the developed model is intended for engineering calculations of the main design HGHEparameters; the model is also applicable to determine the annual specific heat flow as an important parameter in the optimal control system of the HPI. The development of the model is based on the condition of a two-element structure of the soil massif: under the HGHE and above the HGHE; the target parameter is the temperature of the soil mass, depending on the coordinate and time, disclosed through the indicator 'relative temperature rise'; in accordance with the provisions of the thermal conductivitytheory, the relative excess temperature is given for the cases of a semi-infinite body (soil mass under the HGHE) and a slab (soil mass above the HGHE). The proposed model is implemented on the example of two constituent entities of the Russian Federation. The results obtained made it possible to determine the minimum guaranteed possibility of using HPS for heat supply in these climatic conditions. The model presented in the article can be used as a context for further studies of the main parameters of HGHE HPS operation and optimization of HPS operation modes.

Thermal and mechanical creep of clay in hypoplasticity

Clays and clay soils or shales have attracted a lot of interest in a variety of applications, including the development of geothermal resources [1], energy foundations [2], oil exploration [3], energy storage [4], and the storage of nuclear waste [5]. The continued operation of ground source heat pump installations can lead to considerable long-term settlements, which could negatively affect the adjacent or underlying foundations [1]. Therefore, thermal volume change has been widely experimentally investigated in clays [4, 7, 8, 9]. Especially in [4] the authors studied the thermal and mechanical consolidation of saturated marine clays through laboratory element tests, where excess pore pressures were generated by heating samples at constant water content and then allowed to dissipate. In constant stress creep experiments described in [4] it was documented that thermal creep strains typically increased linearly with log time at rates controlled by the prevailing temperature.
 On the other hand, the mechanical time dependency of the stress–strain behaviour of soft soils, especially highly plastic clay, is generally too significant to be ignored [10, 11]. The constitutive modelling of the time-dependent stress–strain behaviour of soils has been an active area of research for five decades and has attracted much attention from the international geotechnical community in recent years as denoted in [12]. In [13] a visco-hypoplastic (VHP) model for normally and overconsolidated clays has been proposed. Probably the most salient feature of hypoplasticity itself is that loading and unloading can be described with only one equation as with the strain and stress rate denoted as and , respectively. The elastic stiffness tensor is represented by ; is the degree of nonlinearity and is the flow rule (direction of hypoplastic strain). The last part of the equation expresses the time-dependent strain rate (i.e. viscous) with the material parameters as the viscosity index and being the compression index. denotes the overconsolidation ratio. As may be observed, the model is not restricted solely to time-dependent clay materials, because does not represent a singularity for the constitutive equation as in other hypoplastic models. The model has been extended in [14] to account for the small-strain stiffness and the mechanical behaviour under cyclic loading. It follows the critical state theory and incorporates a loading surface for the definition of , see Fig. 1A). Time-dependent one-dimensional behaviour of clays is in most cases explained by the isotache framework, which assumes a unique relation between effective stress, strain, and strain rate in compression, shown as loci of constant strain rate in space, see Fig. 1B). The creep deformation at constant effective stress (; Fig. 1C)) corresponds to a decrease in strain rate of the soil (path A to B in Fig. 1C)). Consolidation stress history, represented by swelling along the path AC, causes a marked reduction in compressive creep rates at low (CD), while expansive/dilative creep strains occur at higher (CEE).
 Due to the temperature dependency of the compressibility of clays the isotachs may be considered as temperature dependent as well. As shown in [6] the isotache loci at a given strain rate for normally consolidated states are functions of strain rate and temperature. Increases in temperature cause additional compressive thermal creep strains for NC and lightly OC states (BB and DD in Fig.1C)) and augment the swelling strains at higher (EE).
 In the framework of hypoplasticity, the non-isothermal behaviour has not gained much attention [15]. This work is devoted to the extension of the VHP model formulation to present a unified model for both thermal and viscous strains in clays. The model predictions are assessed through comparisons with existing laboratory experiments from [7] on two clays with measurements of both isothermal/mechanical creep and thermally induced creep strains, providing a thorough calibration scheme as well.

Estimating electric power consumption of in-situ residential heat pump systems: A data-driven approach

International Energy Agency predicts that the global number of installed heat pumps (HP) will increase from 180 million in 2020 to approximately 600 million by 2030, covering 20% of buildings heating needs. Electric power consumption is one of the main key performance indicators for the heat pump systems from techno-economic perspective. However a common issue prevalent in many existing heat pumps is the lack of electric power measurement. The modern installations might be equipped with electric power measurement sensors but this comes at a higher system cost for the manufacturers and end-users. The primary objective of this work is to propose a virtual measurement for estimating power consumption, thereby eliminating the need for field measurement of power for heat pumps. To achieve the objective, a data-driven approach is proposed. Firstly, the in-situ data is preprocessed through data merging, cleaning, and normalization. Then, input features are pre-selected using Spearman correlation coefficients, and further refined by addressing multicollinearity problem. Following this, Extreme Gradient Boosting (XGBoost) models and polynomial models are developed by considering different features as inputs. All models are finally validated against the in-situ data from multi-units of ground source heat pump (GSHP) and air source heat pump (ASHP) installations. The results showed that the electric power consumption of GSHP can be estimated with high accuracy (99% for R2, 10 W for MAE, and 1% for MAPE) through generic data-driven models using only four easy-to-measure input features. Taking three input features as inputs for ASHP generic model, the accuracy can be reached to 83% for R2, 125 W for MAE, and 9% for MAPE. The method presented in this paper can be applied to estimate power consumption of millions of heat pumps and consequently add a significant value as well as provide different types of services, such as cost-saving benefits for manufacturers and end-users, flexibility services for aggregators and electricity grids.

ENHANCEMENT OF ENERGY EFFICIENCY AND BIOSPHORE COMPATIBILITY OF BUILDINGS AND STRUCTURES IN UKRAINE

The use of alternative energy sources is one of the most important areas of modern energy policy, aimed both at improving the environment and saving traditional fuel and energy resources. Adopted legislative and regulatory acts contributed to the rapid growth of "green" energy in Ukraine. The meaning of the ecological and energy optimization process is not to replace one energy source with another, but economic and industrial transformation, decarbonization and decentralization. 
 A technical solution to the problem regarding the source of alternative energy due to the use of heat in the surface layers of the earth's crust is proposed. At the depth of placement of probes-heat exchangers, which are structurally part of heat pump installations, the soil temperature is practically unchanged throughout the year and is positive. Non-freezing glycol solutions are used to increase the operational reliability of the installations. 
 To study the process of thermal interaction in the zone of placement of heat exchanger probes, mathematical modeling using the finite element method was applied. As a result, a significant array of data was obtained, which reflects the dynamics of temperature fields in different modes of operation of ground-source heat pump installations with vertical probes. 
 Of particular interest is the analysis of temperature fields along the depth of the well. After the seasonal selection of heat - the end of the heating period - the minimum temperature of the soil in the boundary zone of the geothermal probe is not lower than 0 0С. That is, freezing of soil rocks does not occur. 
 In the warm period of the year, due to, for example, the working air conditioning system of the building, the energy source of which is the heat pump installation, regeneration of the primary circuit takes place. The average temperature of the rocks between the probes at the beginning of August is, according to calculations, 6.5 0С. 
 The obtained results of analytical studies were used in the design of a ground heat pump installation for the energy supply needs of a public building with an estimated thermal capacity of 200 kW.

Energy efficiency in hospitals: comparative analysis of different HVAC configurations

ABSTRACT The characteristics of health facilities e.g. the need to operate 24 h a day, strict cleaning procedures and indoor environmental parameters made these building-type energy-intensive. The huge potential that can be exploited in terms of energy savings is evident, mainly regarding the HVAC system refurbishment. From literature emerges that there are poor systematic analyses concerning all the possible HVAC retrofit scenarios, considering solutions currently on the market or renewable sources. To fill the research gap pointed out, the present paper proposes a rigorous analysis of the possible generation subsystems available on the market that can be implemented in an HVAC retrofit for a hospital. A real case study of 88,000 m3, represented by a hospital in southern Italy, has been used. Different technologies, such as the photovoltaic system, electric heat pump, absorption heat pump driven by solar energy, cogeneration are analysed from the energy and environmental point of view, with the introduction of the Imported Energy Level Index (IELI). The best retrofit measures is the installation of an absorption heat pump driven by solar thermal collectors and cogeneration, with a primary energy saving of 20%. Considering the installation of a heat recovery unit, the saving is up to 43%.

POSSIBILITIES AND PERSPECTIVES OF THE CONSUMERS-REGULATORS APPLICATION IN SYSTEMS OF FREQUENCY AND POWER AUTOMATIC REGULATION

The Integrated Energy System (IES) of Ukraine functions as part of the European Union (EU) electric power system ENTSO-E. Each country whose IES operates in the ENTSO-E structure must ensure the presence of a full-fledged fre-quency and power automatic control system (AFPCS, AFPC system) in the national IES. The only exception is the IES of Ukraine, because its inclusion in the ENTSO-E happened during martial law and in the absence herewith of a full-fledged AFPC system. It violates the cornerstone requirements of the ENTSO-E structure formation. In the post-war period, the IES of Ukraine will be obliged to complete its own, full-fledged AFPCS as soon as possible. Three structures of the AFPC system development of the Ukrainian IES were studied: according to the traditional principle (on the basis of generators-regulators); on the basis of heat consumers-regulators with the involvement of heat pump installa-tions and on the basis of heat consumers-regulators using electric heat generators that provide energy for the central-ized heat supply system. Calculations and analysis of technical and economic indicators showed that the traditional structure of AFPCS extremely loses to both structures built on consumers-regulators. Significantly better of these two systems is the AFPCS, built on consumers-regulators in the form of electric heat generators. It provides an annual net profit of more than 1.8 billion USD, with a payback period of about 0.5 years, reduces by 2.7 billion m3 of natural gas consumption, reduces by 13.9 billion USD needs capital investment, has short construction deadlines. References 20, tables 5.

Rational Use of Energy in Sports Centres to Achieve Net Zero: The SAVE Project (Part A)

Sports centres constitute major energy consumers. This article presents the proposed energy performance upgrade process and the achieved results for the municipal sports centre in Arkalochori, Greece. The facility consists of a swimming pool centre, an outdoor 8 × 8 football court, and two tennis and basketball courts. It operates with considerably high energy consumption due to the lack of any measure towards its energy efficiency improvement since its initial construction in 2002. Due to the significantly high heating cost, the swimming pool centre remains operative only during the summer period. The energy performance upgrade of the facility was holistically approached through all possibly applicable passive and active measures: insulation of opaque surfaces and replacement of openings, construction of a new, bioclimatic enclosure for the swimming pool’s centre and conversion of the current outdoor facility to an indoor one, installation of heat pumps for indoor space conditioning and swimming pool heating, installation of a solar–combi system for domestic hot water production, upgrade of all indoor and outdoor lighting equipment and installation of a photovoltaic plant on the new enclosure’s roof for the compensation of the remaining electricity consumption. With the proposed measures, the municipal sports centre is upgraded to a zero energy facility. The payback period of the investment was calculated at 14 years on the basis of the avoided energy procurement cost. The swimming pool’s centre operation is prolonged during the entire annual period. This work has been funded by the Horizon 2020 project with the acronym “NESOI” and was awarded the public award of the “Islands Gamechanger” competition of the NESOI project and the Clean Energy for EU Islands initiative.

Development of a Pilot Borehole Storage System of Solar Thermal Energy: Modeling, Design, and Installation

Borehole thermal energy storage systems represent a potential solution to increase the energy efficiency of renewable energy plants, but they generally have to comply with strict regulatory frameworks, mainly due to the deliberate modification of the subsoil’s natural state. This paper presents the design, testing, and monitoring phases carried out to set up a borehole thermal energy storage (BTES) system able to exploit the excess solar heat from photovoltaic thermal (PVT) collectors. The case study is the refurbishment of a pig nursery barn, hosting up to 2500 weaners, in Northern Italy. This study aims to define a BTES suitable to develop a heating system based on renewable energy, ensuring environmental protection and long-term sustainability. The retrofitting intervention includes the installation of a dual-source heat pump (DSHP), in order to recover the solar heat stored in summer during winter. Specific constraints by the Environmental Authority were as follows: maximum storage temperature of 35 °C, authorization to intercept the shallowest aquifer at a maximum depth of 30 m, obligation of BHE grouting, and the definition of a strategy for continuous measuring and monitoring of the groundwater’s thermophysical properties. The results were used as inputs to optimize the design and installation of the integrated system with PVT, BTES, and DSHP.

The subsurface thermal state of Svalbard and implications for geothermal potential

Svalbard is a High Arctic Archipelago at 74–81°N and 15–35 °E under the sovereignty of Norway. All settlements in Svalbard, including the capital of Longyearbyen (population 2400), currently have isolated energy systems with coal or diesel as the main energy source. Geothermal energy is considered as a possible alternative for electricity production, as a heat source in district heating systems or harnessed for heating and cooling using geothermal heat pump installations. In this contribution we present the until now fragmented data sets relevant to characterize and assess the geothermal potential of Svalbard. Data sets include petroleum and deep research boreholes drilled onshore Svalbard, 14 of which have recorded subsurface temperature data at depths below 200 m. Geothermal gradients on Spitsbergen vary from 24 °C/km in the west to 55 °C/km in the south-east, with an average of 33 °C/km. Four deep research boreholes were fully cored and analyzed for thermal conductivity. These analyses were complemented by thermal conductivity calculated from wireline logs in selected boreholes and four measurements on outcrop samples. 1D heat flow modelling on five boreholes calibrated with the measured thermal conductivities offers insights into heat transfer through the heterogeneous sedimentary succession. Offshore petroleum boreholes in the south-western Barents Sea and marine heat flow stations around Svalbard provide a regional framework for discussing spatial variation in heat flow onshore Svalbard, with emphasis on the effects of erosion and deposition on the thermal regime. We conclude that Svalbard's geology is well suited for geothermal exploration and potential production, though challenges related to permafrost, the presence of natural gas, heterogeneous reservoir quality and strongly lateral varying heat flow need to be adequately addressed prior to geothermal energy production. Specifically for Longyearbyen, high geothermal gradients of 40–43 °C/km in the nearest borehole (DH4) suggest promising sub-surface thermal conditions for further exploration of deep geothermal potential near the settlement.

Mathematical Modeling of a Heat Pump Unit in the Climatic Conditions in the Northern Region of Kazakhstan

Currently, the use of heat pumps in the Republic of Kazakhstan is becoming popular. However, there is no introduction of low-potential thermal resources from renewable sources together with the use of heat pumps, which is important in the area of energy conservation and also deemed nature-friendly for the country. The purpose of this work to form a mathematical model of the optimal choice of the working units and calculation of thermodynamic parameters of a heat pump installation, taking into account the design and climatic conditions of the Kostanay region situated in the northern region of Kazakhstan. The conditions of efficiency and the choice of a specific source of thermal energy are considered, which depends on climatic conditions, especially if the source of heat extraction is atmospheric air and earth. The mathematical model of the heat pump unit is formed by studying arithmetic relations in the function of temperature indicators of external and internal environments, which characterizes its effective use in the climatic conditions of the Northern region of Kazakhstan. Based on the developed algorithm of the model’s calculations of heat consumption, the thermal power of the heat pump was made.

Multi-objective evaluation of different retrofitting scenarios for a typical Greek building

In this study, multiple retrofitting scenarios of a typical Greek house were investigated. These scenarios encompass the addition of insulation to the building’s external walls and roof, a green roof construction, the use of high-quality windows and the installation of an efficient heat pump. The aforementioned techniques were simulated separately and in combination with the use of the DesignBuilder software, on an annual basis, for the city of Athens, Greece. The pivotal innovation of this work lays in the energy simulation and the comprehensive comparison of the 34 retrofitting scenarios according to a multi-objective evaluation procedure. An additional novelty was the investigation of the energy impact of each renovation action when applied separately. The goal of the multi-objective evaluation procedure was to determine the optimum renovation case, for maximizing the energy savings and minimizing the life cycle cost. According to the results, the optimum retrofitting case included the installation of insulation to the building’s external surface and the heat pump retrofitting. The optimum scenario resulted in a 41.7% reduction in the building’s heating loads and a 14.9% reduction in its cooling loads. Finally, the primary energy savings were 66.1% and the life cycle cost analysis showed 6,645 € lifespan savings.

Replacing gas boilers with heat pumps is the fastest way to cut German gas consumption

The supply security of fossil gas has been disrupted by the Russo-Ukrainian War. Decisions to relocate the production and transport of gas have become so urgent that new long-term contracts are imminent that undermine the Paris Climate Agreement. Here, we simulate how quickly the addition of renewable electricity and the installation of heat pumps can substitute enough gas to reduce supply risk, while taking a decisive step towards meeting the Paris Agreement. Our bottom-up modelling, using Germany as an example, shows technical pathways on how installing heat pumps is one of the fastest ways to reduce gas consumption, in addition to reducing the load hours of gas-fired power plants. With targeted efforts, maximally 60% of gas from the Russian Federation can be substituted by 2025 with heat pumps and grid expansions, and enough electricity will remain available that the phase-out of coal and the entry into e-mobility will still be practicable.

Optimal Installation of Heat Pumps in Large District Heating Networks

Power-to-heat technology represents a promising solution for the decarbonization of the energy sector. The installation of large-scale heat pumps within district heating systems is widely recognized to be a cost-effective and competitive way to provide flexibility to the electric system, enhancing the use of intermittent renewable energy sources. The goal of this paper is to show how the economic and environmental benefits provided by the installation of a large-scale heat pump in existing district heating systems vary according to the installation location in different scenarios. To do that, an integrated methodology is developed. This includes a physical model of the thermo-fluid dynamic of the district heating network and a detailed modeling of the heat pump. To compare the different positions and also the different operating conditions, an approach based on exergy analysis is adopted. Moreover, a specific control strategy of the mass-flow rate is analyzed to further reduce greenhouse gas emissions. The application to a real large-scale district heating network shows that reductions in CO2 emissions of almost 4% can be obtained by installing a single heat pump of about 4 MWe (over a total thermal load of about 305 MWt), while this positive effect can be reduced by up to 63% if placing the heat pump at non-optimal locations.

Significance of Insulation and Heat Pumps in Decarbonising the UK

This paper examines the economic case for the UK to proceed urgently with the installation of thermal insulation and heat pumps in most UK buildings, in the context of the legal requirement to achieve net-zero carbon emissions by 2050. A recent study by the same authors assumed that such insulation and heat pumps would be in place, and showed how the whole of the UK’s energy demand could be met by low carbon electricity generation and appropriate storage. This paper extends the modelling to consider the risk that insulation is not widely installed, fossil gas boilers are retired (as they must be) but are replaced only by resistive heating, which is the pessimistic but likely outcome in the absence of heat pumps. Unsurprisingly, resistive heating and lack of insulation is shown to consume vastly more electricity: an increase of 608% for space heating and 52% overall. The contribution of this paper is in quantifying the seasonal variations and implications for generation and storage, which make the overall costs increase by an even greater proportion: almost doubling. In particular, peak electricity demand is 130% higher and required peak generation is 140% higher without extra insulation and heat pumps. The paper also illustrates the timely return on capital invested in insulation and heat pumps, primarily because they are cheaper than the additional wind turbines and energy storage required otherwise. The additional costs of failing to insulate and install heat pumps escalate to £63bn per year in levelised energy costs alone, and greatly increase the risk of the UK failing to reach net-zero. The financial break-even point for the costs of retrofitting the entire building stock is shown to be just 15 years from the start of a 28-year retrofitting campaign, with increasing cost savings thereafter. The paper shows that it is both necessary and cost effective to retrofit all buildings with proper insulation and heat pumps.

Building air leakage characteristics and airtightness durability of single-family dwelling

In this study, we focus on the leakage characteristics and composition of openings associated with building airtightness in wooden single-family dwellings. The proposed parallel combination models for leakage are equal to or better than the power law in terms of compatibility with measured values. Unlike reinforced concrete housing complexes, wooden single-family dwellings indicate variability in terms of the coefficient of leakage characteristics, including in highly airtight units. Dwellings constructed approximately 10 years ago do not exhibit a clear declining trend. However, the airtightness decreases in dwellings that have undergone renovations on the outer walls, such as through the addition of an attic or the installation of additional heat pumps.

Project of using low-potential energy sources at the Bratsk hydro power plant

THE PURPOSE. Improving the energy efficiency of a hydroelectric power plant (HPP). Determination of the volume of lost thermal energy from HPP equipment. Development of options for the beneficial use of low-grade heat. Economic evaluation of the proposed options. Selection of the most appropriate waste heat utilization option. METHODS. The methods of the theory of heat and mass transfer, thermodynamic analysis, technical and economic calculations in the energy sector are used in the work. RESULTS. The article determined the temperatures of heat carriers in the cooling system of the hydroelectric generator of the Bratsk HPP. Calculated heat losses in the amount of 92,52 MW. 3 variants of heat supply for the facilities of the Bratsk HPP have been laid. An optimized scheme of heat generation using a heat pump installation (HPI) has been developed. A feasibility study of the proposed options for heat supply has been carried out. An analysis of the Russian HPI market was carried out. A cost-effective heat supply option with 2 Viesmann Vitocal 350-G Pro HPI was selected for implementation with a capital investment 34,46 million of RUB and a payback period of 7,3 years. CONCLUSION. The results of technical and economic calculations show the feasibility of introducing a HPI into the heat generation system of the Bratsk HPP.

Decarbonizing residential buildings with heat pumps: Transferability of front-runner experiences from Swiss Cantons

The replacement of fossil-fuelled heating systems with systems using renewable energy sources is a central energy and climate policy concern and one of the prerequisites for reducing CO2 emissions to a climate-friendly level. The Swiss decarbonization strategy considers the use of electric air-to-water heat pumps (HP) operated with electricity generated from renewable sources or from a power mix with low CO2 content. However, the installation of HPs, which is essential for decarbonizing heat supply in buildings, is proceeding very slowly, and fossil fuel heating replacement is still the rule rather than the exception. This study investigates how a strong climate protection law (Energy Act of Basel-Stadt) has managed to overcome resistance to the installation of HPs, which is observed in many other Swiss cantons. The research question to be answered is whether the experience made with HP implementation in one location (with Basel-Stadt as forerunner canton) would be similarly viable in another location (Canton of Geneva). The results indicate that although the two cantons have different characteristics in terms of building stock, the potential of buildings where HP installation is considered ‘easy’ is high in both cases (50% in Basel-Stadt and 40% in Geneva). This is equivalent to 40% (in both cities) of the energy used for thermal use that is currently produced by fossil energy and that could be instead generated with HPs. Although there are many factors to take into account in order to design effective policies that are truly effective for the extensive installation of HP, it is worth remembering that there are many cases where it is already possible to easily install a HP today, and these should be the starting point.

Perspective Ways of Energy-Efficient Modernization of Heat Supply Systems Based on Heat Pump Technologies

This work is devoted to determination a generalized indicator for a preliminary assessment of the conditions for increasing the efficiency of modernized systems of centralized and decentralized heat supply using heat pump technologies. This goal is achieved through a critical analysis of the results of the actual state of pipelines and equipment, known approaches to the reconstruction of heat supply systems and the establishment of a generalized indicator of the conditions for increasing the efficiency of using primary fuel energy. This made it possible to formulate a generalized approach to the modernization of heat supply systems with the introduction of heat pump technologies. The most important result of the study is the established generalized dependence of the assessment of the increase in the efficiency of heat supply systems on the initial conditions of regime parameters with the rationale for the feasibility of modernizing district heating systems based on the diverse phased introduction of heat pump technologies at all stages: generation, transportation, distribution, conversion and controlled consumption of heat by subscriber system. The significance of the obtained research results lies in the fact that the proposed approach to the modernization of centralized and decentralized heat supply systems based on heat pump installations with real conversion factors in the range (3--5) with an increase in the available heat potential is to increase the efficiency and expand the use of heat from primary fuel with its savings of 1-2.7 times.

Analysis of COVID-19 crisis-related building energy retrofit incentives in Italy

The advent of the COVID-19 pandemic led to an economic crisis of the construction industry and to an increasing of energy consumption in the residential sector for all the world. The European Union highlights the crucial role of building sector for both energy gains and economic growth, defining a “Renovation Wave” plan combining regulation, financing and technical support with the aim of greening the buildings, creating jobs and improving lives. In Italy a great support mechanism for energy refurbishment of existing buildings has been launched by means of tax deduction of 110% over 5 years. The present study aims to analyze this new funding mechanism, under energy, environmental and economic point of views. By means of a real case study, representative of highly widespread southern Italy HVAC-building system, it will be highlighting advantages and contradictions of the incentive mechanism developed, proposing possible future improvements. It is found that, if on one hand, the best refurbishment measure under energy/environmental point of view is the external insulation, windows replacement, electric heat pump and PV-system installation, with a global not renewable performance index reduction of 81%, on the other hand it is not the best solution considering the cost/saving ratio.