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Article

Economic and Ecological Benefits of Thermal Modernization of Buildings Related to Financing from Aid Programs in Poland

by
Janusz Adamczyk
1 and
Robert Dylewski
2,*
1
Institute of Management and Quality Sciences, University of Zielona Góra, ul. Licealna 9, 65-417 Zielona Góra, Poland
2
Institute of Mathematics, University of Zielona Góra, ul. Licealna 9, 65-417 Zielona Góra, Poland
*
Author to whom correspondence should be addressed.
Energies 2026, 19(1), 260; https://doi.org/10.3390/en19010260
Submission received: 16 October 2025 / Revised: 5 December 2025 / Accepted: 7 December 2025 / Published: 4 January 2026
Browse Figure
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Abstract

Improving the energy efficiency of buildings is a highly desirable investment in the context of implementing the sustainable development paradigm, as it reduces the building’s energy demand. Consequently, the economic costs of heating the building are diminished. Reducing the building’s negative environmental impact is also crucial. This article presents programs that subsidize thermal modernization investments for single-family buildings in Poland. Particular attention was paid to the Clean Air program. A methodology for the economic and ecological assessment of thermal modernization investments eligible for funding under this program was proposed. The methodology is based on the Net Present Value indicator, whereas the ecological analysis utilized the Life Cycle Assessment method. A case study was conducted for a model single-family building using the introduced methodology. The scope of the thermal modernization investment included replacing windows and doors, replacing the heat source, and thermal insulation of the vertical external walls. The analyzed thermal modernization investment brings substantial ecological benefits, significantly reducing the building’s negative environmental impact. Unfortunately, the economic viability for the investor is not so obvious and depends primarily on the level of subsidy.

1. Introduction

Energy efficiency is proving to be a key element of the 21st century in improving the relationship between consumers, producers, and the environment. The benefits of improved efficiency have been repeatedly described in the literature [1,2,3]. The need to improve energy efficiency is also highlighted by the Fit for 55 climate package, whose “main” message is the reduction in greenhouse gas emissions [4,5]. It is obvious that by reducing energy demand through improved energy efficiency, we also reduce greenhouse gas emission. Therefore, any investment that contributes to reducing energy demand and greenhouse gas emissions can be classified as eco-efficient.
Pro-efficiency projects also take place in households, where their implementation reduces energy demand. In practice, the energy saved in households is most often consumed by other new devices [6]. However, eco-efficiency projects also include the thermal modernization of residential, commercial, office, and public buildings, etc.
Due to the high percentage of final energy consumption in the European construction sector (40%) [2,7], this sector offers significant opportunities for improving energy efficiency. The construction sector in Poland emitted 57.2 Mt CO2 eq in 1990. Despite actions aimed at improving energy efficiency in Poland, the volume of these CO2 eq emissions in 2022 was “only” 12% lower. At the same time, in the analyzed period (1990–2022), CO2 eq emissions in the waste management sector were reduced by as much as 72% [8]. In Poland in 2020, buildings with a low insulation standard (insulation 8–10 cm thick with high thermal conductivity coefficient) predominated—1,909,000 buildings, which constituted 34.7% of all buildings. Buildings that were not thermally insulated accounted for 32.5% of all single-family buildings [9].
A key factor for high energy efficiency in buildings is the external conditions in which they are constructed. Poland is located in a temperate transitional climate zone, where energy for heating buildings is necessary during winter. A high share of fossil fuels is still used for heating in Poland. Among the 12 European Union countries, Poland ranks second to last in implementing clean heating [10]. In the face of a high level of reluctance of Polish society to replace old inefficient heat sources with new ones, Starościcki [11] proposed a system of incentives in the form of subsidies for scrapping old boilers. This is primarily due to the Polish mentality, habits, economic conditions, and reluctance to change [12]. The state of ecological awareness is also an important element of replacing solid fuel boilers with more energy-efficient heating devices. In a 2016 public opinion poll in Poland on the development of the power sector, the vast majority of Poles supported the development of renewable energy sources, with responses ranging from definitely yes (51%) to rather yes (38%), totaling 89%. In the next question: “Should Poland produce energy using hard coal and lignite due to its abundant resources?”, respondents indicated: definitely yes (22%) and rather yes (41%) [13]. Generally, it can be concluded that Polish society lacks a high level of environmental awareness. The situation is similar in individual boiler rooms in buildings, where hard coal and lignite still account for approximately 21.9% of all energy sources [14,15]. Ciupek et al. [16] note that some investors who have decided to replace old solid fuel boilers with new ones are using them incorrectly, contributing to high emission levels that are completely different from the characteristics of the given boiler. This study confirms that the European Union have taken the right direction, suggesting abandoning fossil fuel boilers in favor of heat pumps or electric heating [17].
Economic conditions also pose a significant barrier to implementing clean heating. In Poland the minimum wage is 1091 EUR (data for 2025) [18], which places Poland within the European average. It is estimated that in 2025 approximately 3.1 million workers will receive the minimum wage [19], hence the economic situation of Polish households is not favorable. Low household incomes constitute a significant barrier to efficiency investments [11]. Hence, aid programs supporting improved efficiency in residential buildings are crucial.
A thermal modernization investment is one element of implementing the sustainable development paradigm, not only because it reduces air pollutant emissions and energy demand, but above all because it reduces the use of energy resources. The essence of thermal modernization projects, in the context of sustainable development, is to ensure that the environmental impact associated with the production of thermal insulation materials, transport, and installation does not exceed the ecological benefits that thermal modernization will provide due to reduced energy consumption. The literature on the subject contains a large number of scientific articles presenting research results in this area [20,21,22,23,24]. Most of the literature uses the Life Cycle Assessment (LCA) technique to assess environmental impact [25], which is based on the formalized methodology described in the ISO 14040 [26] and ISO 14044 [27] standards. In this study, the LCA technique was used to assess environmental impact to determine the ecological benefits of building thermal modernization.
The aim of this study was to provide an integrated assessment of the economic and ecological effectiveness of a thermal modernization investment in the context of various groups of beneficiaries of the “Clean Air” program. The obtained research results allow for recommendations regarding investor support policies for thermal modernization projects aimed at achieving the assumptions of the sustainable development paradigm. The integrated assessment was conducted using a standardized LCA method and economic indicators (NPV, Tp) and ecological indicators (NPVE, TpE). It is difficult to identify a work in the literature that addresses this topic, suggesting a research gap in this area. The analysis was conducted on a single-family detached building constructed in Poland, which requires thermal modernization. The article deliberately did not analyze residential units in multi-family buildings due to the different types of programs that subsidize thermal modernization investments in such buildings. This aspect may be the subject of future research.
Section 2 presents the Clean Air program, which subsidizes thermal modernization investments in single-family buildings in Poland. Section 3 proposes a methodology for the economic and ecological assessment of thermal modernization investments eligible for funding under the Clean Air program. The next section conducts a case study of a model single-family building using the introduced methodology. This is followed by a discussion of the results and conclusions from the conducted research.

2. Programs Co-Financing Thermal Modernization of Single-Family Buildings

In Poland there are several financial instruments available to support these investments. The flagship program is the Clean Air program, established in September 2018 and scheduled to run until the end of December 2030 [28,29]. The Clean Air program is a government initiative aimed at improving air quality in Poland by modernizing heating systems in single-family homes. Funding is available for replacing old coal-fired furnaces, thermal modernization of buildings, and installing renewable energy sources. The program provides grants, loans, and a combination of both forms of aid. Due to beneficiary abuse, this program was temporarily closed but will resume operations from the end of March 2025 under new rules. The subsidy amount is divided into three levels, depending on the applicant’s income. The first (basic) level of subsidy covers beneficiaries whose annual income does not exceed 135,000 PLN (≈32,142 EUR), with a subsidy amounting to up to 40% of eligible costs, up to a maximum of 68,040 PLN. The second (increased) level of subsidy covers beneficiaries whose monthly income does not exceed 2250 PLN/person in a multi-person household and 3150 PLN/person in a single-person household. The subsidy amount at this level is up to 70% of eligible costs, but not more than 119,070 PLN. The highest level of funding for thermal modernization investments is available to beneficiaries whose monthly income is less than 1300 PLN/person in a multi-person household or 1800 PLN/person in a single-person household. Funding at this highest level covers up to 100% of eligible costs, but not more than 170,100 PLN.
It is worth noting that income thresholds that determine the amount of funding for thermal modernization investments have changed for the higher and highest levels, compared to the previous Clean Air program (since 2024). The maximum investment funding has also been revised, making it more realistic in terms of its amount. It is necessary to note that the cost of a comprehensive thermal modernization investment, which involves replacing the heat source, thermally insulating building walls and central heating and domestic hot water pipes, and replacing window and door joinery, fluctuates around the highest funding level.
A prerequisite for obtaining funding under the Clean Air program is ownership or co-ownership of a single-family building for at least three years. Moreover, (for a group of four beneficiaries—see Table 1), for the highest level of funding, the building must meet the criterion of high usable energy demand (over 140 kWh/(m2 year)). Furthermore, there are limits on eligible costs and maximum subsidy amounts for individual construction projects. If the beneficiary decides to replace an old heat source with a heat pump, the selected heat pump must be included on the list of “green devices and materials”.
The Clean Air Program subsidizes thermal modernization projects based on the building′s energy demand prior to thermal modernization. If the building′s energy demand prior to the investment is below EU = 80 kWh/(m2 year), funding is only available for replacing the heat source and the highest level of funding is not applicable (see Table 1-Group 4). If the building′s energy demand prior to the thermal modernization investment is between 80 and 140 kWh/(m2 year), funding is available for replacing the heat source and/or thermal modernization. In this case, the highest level of funding is not applicable (Group 4 beneficiaries). The highest level of funding applies to buildings whose energy demand is higher than EU = 140 kWh/(m2 year). The Clean Air Program subsidizes thermal modernization investments for buildings that meet the above criteria.
Due to previous legal requirements in Poland (concerning maximum heat transfer coefficients), energy demand in buildings constructed between 1989 and 2000 is high. Twenty six percent of single-family buildings constructed during this period have zero wall insulation standard (no insulation). Four percent of buildings have a very low standard (up to 7 cm of insulation with a high thermal conductivity coefficient), and 38% have a low insulation standard (8–10 cm of insulation with a high thermal conductivity coefficient). Therefore, a building constructed in 2000 was adopted as a case study [9].
There are also other programs available in Poland to support thermal modernization investments, such as Stop Smog or Thermal modernization tax credit. The remaining part of this article discusses the financing of thermal modernization investments under the Clean Air program, taking into account the income threshold. This is intended to approximate the value of economic and ecological benefits for investors with varying income levels. This integrated assessment of thermal modernization investments aims to demonstrate the effectiveness of the subsidy system for these investments.

3. Methodology of the Assessment

The study used LCA due to its holistic approach to environmental impact assessment. As noted earlier, this analysis is often used to assess the impact of human economic activity, not only in the construction sector. LCA allows for assessment using a variety of available methods. The method is based on the inventory phase (LCI), in which the investigator summarizes the material and energy inputs and outputs of the processes being assessed. The LCA analysis takes into account the environmental impact associated with producing building materials necessary for improvements to the building′s energy efficiency, such as through replacing windows and doors, replacing the heat source, and insulating vertical external walls.
The economic aspect of thermal modernization investment was also assessed. Beneficiaries of the Clean Air in Poland subsidy program are property owners whose annual income cannot exceed 135,000 PLN/year (≈31,395 EUR/year). All investors were divided into four groups. The first group included investors who, due to their annual income, were unable to benefit from the subsidy. The remaining three groups comprised beneficiaries who, depending on their annual income, receive varying levels of subsidy (see Table 1). The economic analysis of the various investor groups aimed to determine the economic benefits of the investment (Net Present Value, discounted payback period). The same scope of construction work related to the thermal modernization of the building was assumed for each investor group.
The proposed methodology is presented in the flowchart (see Figure 1).

3.1. Economic Assessment Methodology

In economic analysis, to apply the Net Present Value (NPV) indicator, it is necessary to determine the economic costs associated with implementing the investment and the economic profits generated in subsequent years [30]. In the case of funding from the Clean Air program, the economic profit for the investor—the amount of funding—was additionally taken into account. The economic costs are related to the replacement of windows and doors, replacement of the heat source, and thermal insulation of vertical external walls. However, economic profits arise as a result of the reduction in energy demand for heating the building. The NPV can be calculated using the following formula:
NPV = −P0 + D + Pi ∙ SN [PLN],
where
P0—economic costs of the investment, including replacement of windows and doors, replacement of heat source, and thermal insulation of vertical external walls [PLN];
D—amount of funding from the Clean Air program [PLN];
Pi—economic profits related to the reduction in energy demand for heating the building, i = 1, 2, …, N [PLN/year];
SN = sum (i = 1, …, N) [(1 + s)/(1 + r)]i–cumulative discount factor;
N—duration of use of investment effects [years];
r—real annual interest rate;
s—real annual increase in heating costs.
The discounted economic payback period Tp is the time after which NPV (Tp) ≥ 0, and for t < Tp we have NPV (t) < 0, whereas
NPV (t) = −P0 + D + Pi ∙ St [PLN]
is the economic value of the investment, taking into account the profits Pi from years i = 1, 2, …, t.

3.2. Ecological Assessment Methodology

The ecological analysis utilizes the Life Cycle Assessment (LCA) method described in the ISO 14040/14044 standards. The method consists of four phases, where the first phase requires clarification of, among other things, the functional unit and system boundaries. These analysis elements are presented in Section 4.2. The second phase of the LCA analysis consists of an LCI (Life Cycle Inventory Analysis), where the analyst collects all material and energy inputs and outputs. The results of this analysis are summarized in Tables 4 and 5. The third phase is an LCIA (Life Cycle Impact Assessment), where the analyst uses (mandatory) classification and characterization procedures, as well as normalization and weighting procedures. The results of the weighting procedure using the ReCiPe assessment method and the results of the characterization procedure using the IPPC GWP 20a assessment method are summarized in Tables 4 and 5. The results of the weighting procedure in the ReCiPe method are expressed in points [Pt], whereas in the IPPC GWP 20a method, there is no normalization or weighting procedure and the results are expressed in [kg CO2 equivalent]. A computer program is used to perform the LCA analysis, which supports the analyst. The obtained LCA results were used to evaluate the environmental benefits according to the formulas below.
For ecological analysis, the Ecological Net Present Value (NPVE) indicator was proposed, in which ecological costs are related to the implementation of the investment and ecological benefits are obtained by reducing the environmental burden in subsequent years (due to reduced energy demand for heating the building). This indicator was developed based on the NPV model. It takes into account the same factors for costs and benefits, but focuses on ecological aspects rather than economic ones. Furthermore, LCA technique was used to determine both ecological costs and benefits. The NPVE can be calculated using the following formula:
NPVE = −P0E + PiE ∙ N [Pt],
where
P0E—ecological costs of the investment, including replacement of windows and doors, replacement of heat source, and thermal insulation of vertical external walls [PLN];
PiE—ecological profits related to the reduction in energy demand for heating the building, i = 1, 2, …, N [Pt/year];
N—duration of use of investment effects [years].
Similarly to the economic assessment, the discounted ecological payback period TpE, is the time after which NPVE (TpE) ≥ 0, and for t < TpE we have NPVE (t) < 0, whereas
NPVE (t) = −P0E + PiE ∙ t [Pt]
is the ecological value of the investment, taking into account the profits PiE from years i = 1, 2, …, t.

4. Case Study

The model building was constructed in 2000, and five different locations were considered, taking into account five different climatic zones in Poland. The locations considered were Szczecin (zone I), Zielona Góra (zone II), Warsaw (zone III), Białystok (zone IV), and Suwałki (zone V) (according to PN-EN 12831 [31]), in accordance with the Kȍppen–Geiger—Dfb classification [32], with a usable area of 133.10 m2.
Climatic conditions similar to those in Poland (Dfb) occur throughout Central Europe (e.g., the Czech Republic, Slovakia, northeastern Germany) and Eastern Europe (Lithuania, Latvia, Estonia, Ukraine). This type of climate can also be identified in some Northern European countries (Norway—southern interior, Sweden—southern regions) and in a minority in Southern Europe (Croatia—Gorski Kotar, Bulgaria—the city of Sofia and the highlands) [33].
In Section 4.1, Section 4.2 and Section 4.3, an analysis of economic and ecological benefits was carried out for the building located in the city of Zielona Góra (zone II). The demand for usable energy depending on the climate zone is summarized in Table 1. Section 4.4. analyses the economic and ecological benefits for a building located in different climatic zones (Table 1).
The building was constructed using masonry technology with aerated concrete blocks, where the heat transfer coefficient U = 0.40 W/m2K. The windows are double-glazed PVC, where U = 2.60 W/m2K. The building has a gable wooden roof insulated with mineral wool, where U = 0.28 W/m2K. The ground floor is insulated with polystyrene, where U = 0.31 W/m2K. The building’s usable energy demand is EU0 = 144.41 kWh/(m2year). The heating energy demand was calculated using the CERTO computer program [34]. The building is equipped with a coal-fired combi boiler. According to the Clean Air program guidelines, a building with an energy demand exceeding 140 kWh/(m2year) is eligible for heat source replacement and thermal modernization. The condition that must be met to receive funding is that the usable energy value after thermal modernization cannot exceed 140 kWh/(m2year), and the reduction in this indicator must be at least 40%. The building includes the replacement of windows and doors, replacement of heat source, and thermal insulation of the vertical external walls. Despite switching the thermal energy source to a low-temperature source, the radiators were not replaced. As noted by Roca Reina, J.C. and others [35], a low-temperature source can work effectively with “old” radiators due to the frequent oversizing of radiator surfaces in buildings.
After replacing the windows with Uw = 0.9 W/m2K and thermal insulation with 15 cm thick polystyrene, λ = 0.037 W/mK, where Up = 0.18 W/m2K, the demand was EU = 81.43 kWh/(m2year). This means that the demand for usable energy was reduced by almost 44%.

4.1. Economic Benefits of the Building’s Thermal Modernization Investment

The analysis of the economic benefits of building thermal modernization takes into account the cost of replacing the thermal energy source, installing thermal insulation, and replacing windows and doors. Additionally, the Clean Air program funding system was considered, divided into four groups of beneficiaries/investors (see Table 2). The first group consists of investors whose annual income exceeds 135,000 PLN. The income level of this group of investors disqualifies them from receiving funding from the Clean Air program.
The cost of the thermal modernization investment is as follows. Based on calculations of the building′s thermal energy demand after thermal modernization, a PANASONIC All in One 12 kW split heat pump was selected, which provides seasonal energy efficiency in heating, for a moderate climate (water 35 °C/water 55 °C) (SCOP = 4.83/3.44), with a purchase cost of 30,300 PLN [36]. Installation costs should be added to the purchase cost, which averages 6000 PLN.
The average cost of purchasing triple-glazed PVC windows is 800 PLN/m2. The building’s window area is 29.53 m2. The purchase price for the windows is 23,624 PLN, plus 3000 PLN for installation, for a total investment of 26,624 PLN. The cost of replacing doors, including installation, is approximately 3300 PLN.
The exterior wall area is 208.21 m2, and the cost of purchasing polystyrene, installation materials, polystyrene adhesive, mesh adhesive, and acrylic plaster is 16,164 PLN. The average labor cost is 20,821 PLN, for a total investment value of 36,985 PLN.
An economic analysis was performed according to Formulas (1) and (2), taking into account the subsidy groups. The results are summarized in Table 3. The investment service life was assumed to be N = 20 years (adopted on the basis of [37,38]), and the rates r = 5% and s = 3% (adopted on the basis of [37]). When determining the energy costs for heating the building, the costs for the hard coal boiler were assumed to be 0.296 PLN/kWh and for the heat pump 0.294 PLN/kWh (SCOP = 3.5).
As can be seen from Table 3, in the case of group 4, funding can be obtained in the amount of full investment costs. For groups 1 and 2, a negative NPV was obtained. The investment for these groups will not pay off within N = 20 years, resulting in Tp > N.

4.2. Ecological Benefits of the Building’s Thermal Modernization Investment

The LCA analysis was conducted using the SimaPro computer program (version 6.2) and the ReCiPe (E) method. This method allows for the presentation of assessment results expressed in [Pt] using a weighting procedure [34]. An important element of the LCA analysis is the input data inventory phase. The system boundaries encompass the production process of equipment and construction materials used in the thermal modernization investment. The environmental impact associated with the transport of these materials and equipment was not included within the system boundaries due to their marginal significance. Transport is a variable dependent on the distance separating, in this case, the wholesaler from the building where the investment is being carried out. Due to the nature of this variable, the impact of transport on the environment was omitted. The post-consumer phase was also not included due to the considered service life of N = 20 years. Due to the specific nature of the environmental impact assessment for a thermal modernization investment, various functional unit values were assumed (see Table 4 and Table 5).
The Ecoinvent 3.0 database was used to assess the environmental impact of the heat pump production process. Two methods were used in the study to assess the environmental impact: ReCiPe (E) and IPCC 2013 GWP 20a. In the ReCiPe method, the analysis result is expressed in the unit [Pt], while in the IPCC method it is expressed in [kg CO2 equivalent]. Similarly, this database was used to assess the environmental impact of the thermal energy production process of the previous heat source, a hard coal-fired boiler; thermal energy production of the heat pump; and the production of building materials: polystyrene, polystyrene/mesh adhesive (the Ecoinvent database does not distinguish between the two types of adhesive; the same type of adhesive was assumed for both cases), acrylic plaster (due to the lack of data in the Ecoinvent database, acrylic paint was assumed), polystyrene plugs, and façade-reinforcing mesh. The LCI analysis of windows is based on the publication by Kowalczyk et al. [39], in which the authors assessed energy-efficient windows.
The LCA analysis results (see Table 4 and Table 5) provide information on the environmental impact of the thermal modernization investment. Each device and product impacts the environment through the acquisition of raw materials and the production process. It is important for the environment that the increased environmental impact resulting from the thermal modernization process is offset by lower pollutant emission during the building′s service life. In our case, a different thermal energy source was used, and energy demand was reduced due to the thermal insulation of the building′s walls.
The highest environmental impact is achieved by generating thermal energy using a hard coal-fired boiler. This boiler is characterized by low efficiency compared to a heat pump, and the LCA result for thermal energy production is more than six times higher than that of the heat pump. According to the principles of LCA, comparative analyses of products can only be conducted within the same functional unit. The secondary objective of this article was to compare the environmental impact of a thermal modernization investment that meets the lowest requirements of the Clean Air program. The total environmental impact of this investment over a 20-year period is 9183.08 Pt.
An ecological analysis was performed using Formulas (3) and (4). The results are summarized in Table 6. The service life was assumed to be N = 20 years, as in the economic analysis. Taking into account ecological aspects, the investment is very profitable and will pay for itself after just 1 year.
To summarize the results, it should be noted that the analyzed thermal insulation investment brings substantial ecological benefits, significantly reducing the building’s negative environmental impact. Unfortunately, the economic viability for the investor is not so obvious and depends on the level of subsidy. For investors in group 1, who are not eligible for subsidy, the payback period would only be 85 years, much later than the assumed 20-year period. Consideration should be given to providing this group with subsidies or to raising the upper limit of annual income, given the significant environmental benefits.

4.3. Sensitivity Analysis

This section examines how changes in the investment use time N, economic costs P0, and ecological costs P0E affect the results of economic and ecological analyses.
Table 7 summarizes the results for times N = 15, 20, and 25 years. Of course, as time N changes, the discounted payback period Tp and TpE does not change. In the case of economic analysis, the situation in the individual groups does not change. For each N, in groups 1 and 2, the investment is economically unprofitable, and in groups 3 and 4, it is economically profitable. Only when N < 15 years, in group 3, would the investment be economically unprofitable. In the case of ecological analysis, the NPVE is lower by about 26% for N = 15 years and higher by about 26% for N = 25 years.
Table 8 summarizes the results of economic analysis for economic costs P0 that are 10% lower and higher. For both −10% and +10% changes in economic costs, the investment remains economically unprofitable in groups 1 and 2, while it remains economically profitable in group 3. In group 4, the NPV does not change due to subsidy equal to the full costs. As costs change, the payback period changes significantly with lower subsidy levels, with the greatest impact in group 1.
Table 9 presents the results of ecological analysis for P0E ecological costs that are lower and higher by 10%. A change in ecological costs by +/−10% has a negligible impact on the investment’s ecological profitability; NPVE changes by less than 0.5%. In each case, the payback period is 1 year.
Table 10 summarizes the results of economic analysis for various changes in heating energy costs. The baseline assumed an annual heating cost increase in s = 3%. For both s = 2% and s = 4%, the investment is still economically unprofitable in groups 1 and 2, while it is still economically profitable in groups 3 and 4. Obviously, the greater the increase in heating costs, the more economically profitable the investment is, and the shorter the payback period.

4.4. Economic and Ecological Analysis Depending on the Climate Zone

This section presents a comparative analysis of the benefits depending on the climate zone in which the building is located (see Table 1). The climate zone influences both economic and ecological benefits. The results are summarized in Table 11. For climate zone I, the building’s energy demand is EU0 = 133.54 kWh/(m2year) (see Table 1), hence there is no subsidy in Groups 2–4.
For climate zones II–V, in groups 1 and 2, the investment is economically unprofitable, and in groups 3 and 4, it is economically profitable. It can be observed that the higher the group number, the shorter the payback period Tp and the higher the NPV. In the case of ecological analysis, the ecological benefits NPVE are very high in each zone, with small differences. The payback period TpE always occurs after one year.

5. Discussion

Summarizing the results obtained in Section 4 regarding the economic analysis, it can be observed that only for Groups 3 and 4 is the payback period Tp shorter than the assumed useful life of N = 20 years, and the Net Present Value NPV positive. However, in the ecological analysis, the ecological Net Present Value NPVE is always very high, and the payback period TpE is only 1 year.
The scientific objective of this article was to assess the impact of the Clean Air subsidy program on economic and ecological conditions, broken down by beneficiary group. The research methodology was based on the analysis of material and energy inputs to the production processes of materials and equipment, using the LCI assessment stage, necessary to conduct a “medium” level of thermal modernization. Furthermore, an economic assessment was performed using the NPV indicator, and payback periods Tp were determined. In the publication [40], T. E. Szafranko analyzed a single-family building located in Poland combined with three variants of wall thermal insulation. She obtained similar research results; the investment was also subsidized by the earlier Clean Air program. The payback periods for these investments were long, ranging from 15.9 to 21.2 years. Liu W. et al. analyzed a building constructed in 1994 in the Netherlands, in the context of improving its energy efficiency. They obtained results similar to those of this study, where the payback period for the thermal modernization investment ranged from 6 to 56 years [41]. Zawada B. and Rucińska J., analyzing a single single-family building located in Warsaw, obtained a simple payback period of 56–66.2 years without taking into account subsidies [42].
Labanca, N. et al. [43] note that there are many barriers to implementing energy efficiency concepts in the construction sector. They identify, among other things, long payback periods for thermal modernization investments and a lack of appropriate financing options, which confirm the research results. Financial instruments of energy policy are effective when the investor achieves measurable savings from reduced operating costs, which compensate for the financial outlays incurred during the investment’s useful life. Environmental benefits resulting from a thermal modernization investment, given a low level of environmental awareness, may prove to be an insufficient reason for the investor to decide to carry out this investment.

6. Conclusions

Despite the seemingly regional nature of this article, every action aimed at improving energy efficiency in a member state also has an impact on reducing cross-border pollutant emissions in other neighboring countries. Furthermore, the article can be considered a guide to good practices for subsidizing thermal modernization investments in other European Union countries and worldwide. Moreover, much of Europe falls under the Dfb climate category (Kȍppen–Geiger classification), the same as Poland. In many European countries, as in Poland, there are programs that co-finance thermal modernization investments—for example, in the Czech Republic—Nová zelená úsporám (New green savings program), in Germany—Bundesförderung für effiziente Gebäude (BEG) Förderprogramm (The Federal Funding for Efficient Buildings), or in Slovakia—Obnov dom (Renovate your home). It should be noted that the conditions for financing these investments vary between countries; however, financing support programs are most effective when investors can generate returns from the investment within a short period of time. This financial instrument of energy policy is intended to encourage potential beneficiaries to invest, with the expectation that economic benefits will appear shortly after the project’s completion. The most important conclusions resulting from the research are presented below:
  • Considering environmental aspects, subsidizing thermal modernization investments is entirely justified. Within the first year of a building’s use after completion of the thermal modernization project, the environmental costs are already offset by the benefits resulting from reduced energy demand for heating.
  • Subsidies improve the economic viability of the investment and increase investors’ motivation to thermally modernize the building. However, the economic viability of a thermal modernization investment is also determined by external economic factors such as inflation, rising prices, and increased purchasing power. High inflation reduces the value of available financial resources, including those derived from subsidies, which can be a barrier for potential investors. Therefore, it is recommended that the subsidy amount under the Clean Air program (and any other financial investment support program) should be revalued, for example, annually, taking into account the current inflation rate and price dynamics in the construction materials and services market.
  • A building’s thermal modernization project, funded by the Clean Air program, can be implemented for a maximum period of 30 months. During this time, the investor is exposed to the risk of rising investment costs, which may lead to the need to abandon the investment and funding. When budgeting for the investment, the investor bases it on current prices. Even if an energy audit is performed before the thermal modernization project begins, there is no guarantee that the specified payback period will be realistic. This risk, borne by the investor, can be relatively reduced by periodic revaluation of the subsidy amount. The above study confirms the proposed change to the Clean Air program, where the high costs of construction materials and services, resulting from high inflation in Poland and geopolitical turmoil, do not guarantee a return on thermal modernization investments, even with program funding (group 2). It should be noted that the primary goal of the Clean Air program is not to provide financial security for investors, but to reduce the environmental pressure of the construction sector.
  • Reducing the risk of thermal modernization investment failure by revaluing the subsidy amount is particularly important for beneficiaries with the lowest income levels (groups 4 and possibly 3), where the level of income generated prevents the investment from being implemented.
  • State intervention also seems justified, with targeted subsidies directed at various groups of beneficiaries. Investors with high annual incomes are excluded from financial assistance. The subsidy program is aimed at poorer beneficiaries to prevent social exclusion. Despite the demanding requirements for beneficiaries in preparing documentation for the Clean Air program, the assumptions and implementation of this program are socially, ecologically, and economically motivated.
  • Implementing a program subsidizing thermal modernization investments aligns with the canon of the sustainable development paradigm.
  • From an economic perspective, an investor who does not qualify for subsidies (income exceeding 130,000 PLN) will not receive reimbursement for their costs over a 20-year period. Construction material prices in Poland were on a steady upward trend, with a record 33% increase recorded in 2022. Prices for these materials stabilized only in 2025. The price of fuel for the modernized heating source also impacts the investor’s economic situation.
  • The geopolitical situation has significantly impacted energy prices in Poland and globally. Despite the increase in energy prices, investors from groups 1 and 2 will not receive a return on investment within the considered 20-year period of use of thermal insulation.
  • Due to the unfavorable energy mix, where “dirty” electricity from coal combustion predominates, the end user is burdened with the consequences of the ETS 1 system, namely the carbon dioxide emission fee. Furthermore, a new ETS 2 system is expected to enter the market, aimed at introducing equality among individual users of heat sources. Social inequality among users of various heat sources results in the fact that owners of single-family buildings using, for example, heat pumps or electric heating pay an additional fee under ETS 1 system when paying for electricity consumption. Other users of boilers fired with coal, gas, heating oil, wood, and pellets do not pay the CO2 emission fee. This situation is expected to change in the coming years. Nevertheless, future changes will not necessarily improve the economic conditions for thermal modernization investments.
  • Despite the lack of economic benefits, an investor with a high annual income benefits primarily from thermal comfort through a thermal modernization investment, which improves the quality of life for all building users. Moreover, by using more environmentally friendly heating equipment that emits less carbon dioxide and other pollutants, the investor impacts local and regional air quality, improving the quality of life for their neighbors, both near and far. These aspects are difficult to economically assess and are often overlooked in this type of investment. Furthermore, as demonstrated in the study, a thermal modernization investment is environmentally friendly and environmentally sustainable. A thermal modernization investment is conditioned environmentally, socially, and sometimes economically, which largely depends on the economic situation.

Author Contributions

Conceptualization, J.A. and R.D.; methodology, J.A. and R.D.; software, J.A. and R.D.; validation, R.D.; formal analysis, J.A. and R.D.; investigation, J.A. and R.D.; resources, J.A.; data curation, J.A. and R.D.; writing—original draft preparation, J.A. and R.D.; writing—review and editing, J.A. and R.D.; supervision, J.A.; project administration, J.A. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

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Energies 19 00260 g001
Figure 1. Flowchart for the proposed methodology.
Figure 1. Flowchart for the proposed methodology.
Energies 19 00260 g001
Table 1. Demand for usable energy depending on the climate zone.
Table 1. Demand for usable energy depending on the climate zone.
Poland’s Climate ZonesIIIIIIIVV
Building’s usable energy demand EU0 [kWh/(m2Year)]133.54144.41143.70166.33178.42
Building’s usable energy demand EU [kWh/(m2Year)]74.1281.4380.0595.50104.13
Reducing the demand for usable energy44.5%43.6%44.3%42.6%41.6%
Building location (city)SzczecinZielona GóraWarszawaBiałystokSuwałki
Table 2. Maximum subsidy amounts from the Clean Air program for individual funding levels.
Table 2. Maximum subsidy amounts from the Clean Air program for individual funding levels.
Type of Beneficiary(Group 1)
Income Above 135,000 PLN/Year		(Group 2)
Basic Level
Income Below 135,000 PLN/Year		(Group 3)
Higher Level
Income: 2250 PLN/Person Month or 3150 PLN/Person Month		(Group 4)
Highest Level
Income: 1300 PLN/Person Month or 1800 PLN/Person Month
Maximum subsidy for replacing the heat source with an air/water heat pumpNo funding14,520.0025,410.0036,300.00
Maximum funding for thermal insulation of vertical walls and window replacementNo funding26,763.6046,836.3066,909.00
Table 3. Results of economic analysis.
Table 3. Results of economic analysis.
Group 1Group 2Group 3Group 4
P0 [PLN]103,209.00103,209.00103,209.00103,209.00
D [PLN]0.0041,283.6072,246.30103,209.00
Pi [PLN/year]2499.842499.842499.842499.84
NPV [PLN]−62,102.30−20,818.7010,144.0041,106.70
Tp [years]8535151
Table 4. Results of LCA analysis of the thermal modernization project.
Table 4. Results of LCA analysis of the thermal modernization project.
Heat PumpThermal Energy Production—Hard Coal
(60% Efficiency)		Thermal Energy Production—Heat Pump
(SCOP = 3.50)
Functional unit1 pc.1 kWh1 kWh
LCA analysis result [Pt]10500.2070.031
LCA analysis result
[kg CO2 eq]		36001.780.30
Total result of the LCA analysis for the building1050 Pt3972.33 Pt/year
79,446.68 Pt/20 years		331.34 Pt/year
6626.87 Pt/20 years
Table 5. Results of LCA analysis of the thermal modernization project continued.
Table 5. Results of LCA analysis of the thermal modernization project continued.
Acrylic Plaster + Primer EmulsionStyrofoam DowelsFiberglass MeshGraphite Styrofoam,
15 cm Thick		Glue for Polystyrene/MeshWindows, PVC Doors
Functional unit1 kg1 kg1 m21 m21 kg1 m2
LCA analysis result [Pt]0.6120.2430.1931.140.26512.3
LCA analysis result
[kg CO2 eq]		3.052.362.2811.11.48108
Total result of the LCA analysis for the building 388.62 Pt1.458 Pt12.06 Pt237.36 Pt503.50 Pt363.22 Pt
Table 6. Results of ecological analysis.
Table 6. Results of ecological analysis.
P0E [Pt]2566.22
PiE [Pt/year]3640.99
NPVE [Pt]70,263.60
TpE [years]1
Table 7. Impact of the investment’s useful life on the results of economic and ecological analyses.
Table 7. Impact of the investment’s useful life on the results of economic and ecological analyses.
N = 15 yearsN = 20 yearsN = 25 years
Group 1NPV [PLN]−70,947.46−62,102.30−54,068.05
Tp [years]858585
Group 2NPV [PLN]−29,663.86−20,818.70−12,784.45
Tp [years]353535
Group 3NPV [PLN]1298.8410,144.0018,178.25
Tp [years]151515
Group 4NPV [PLN]32,261.5441,106.7049,140.95
Tp [years]111
-NPVE [Pt]52,058.6470,263.6088,468.55
TpE [years]111
Table 8. Impact of the change in economic costs on the results of economic analysis.
Table 8. Impact of the change in economic costs on the results of economic analysis.
P0 − 10%P0 [PLN]P0 [PLN]P0 + 10%P0 [PLN]
Group 1NPV [PLN]−51,781.40−62,102.30−72,423.20
Tp [years]6785112
Group 2NPV [PLN]−14,626.16−20,818.70−27,011.24
Tp [years]303540
Group 3NPV [PLN]13,240.2710,144.007047.73
Tp [years]131516
Group 4NPV PLN]41,106.7041,106.7041,106.70
Tp [years]111
Table 9. Impact of changes in ecological costs on the results of ecological analysis.
Table 9. Impact of changes in ecological costs on the results of ecological analysis.
P0E − 10%P0E [PLN]P0E [Pt]P0E + 10%P0E [PLN]
NPVE [Pt]70,519.2270,263.6070,007.98
TpE [years]111
Table 10. Impact of changes in heating costs on the results of economic analysis.
Table 10. Impact of changes in heating costs on the results of economic analysis.
s = 2%s = 3%s = 4%
Group 1NPV [PLN]−65,814.61−62,102.30−57,922.81
Tp [years]-8553
Group 2NPV [PLN]−24,531.01−20,818.70−16,639.21
Tp [years]453529
Group 3NPV [PLN]6431.6910,144.0014,323.49
Tp [years]161514
Group 4NPV [PLN]37,394.3941,106.7045,286.19
Tp [years]111
Table 11. Economic and ecological analysis depending on the climate zone.
Table 11. Economic and ecological analysis depending on the climate zone.
Poland’s Climate Zones IIIIIIIVV
Group 1NPV [PLN]−64,436.05−62,102.30−61,673.42−56,963.94−54,690.02
Tp [years]9985826560
Group 2NPV [PLN]-−20,818.70−20,389.82−15,680.34−13,406.42
Tp [years]-35343028
Group 3NPV [PLN]-10,144.0010,572.8815,282.3617,556.28
Tp [years]-15151312
Group 4NPV [PLN]-41,106.7041,535.5846,245.0648,518.98
Tp [years]-1111
-NPVE [Pt]64,878,4070,263.6069,985.3081,177.7887,126.73
TpE [years]11111
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Adamczyk, J.; Dylewski, R. Economic and Ecological Benefits of Thermal Modernization of Buildings Related to Financing from Aid Programs in Poland. Energies 2026, 19, 260. https://doi.org/10.3390/en19010260

AMA Style

Adamczyk J, Dylewski R. Economic and Ecological Benefits of Thermal Modernization of Buildings Related to Financing from Aid Programs in Poland. Energies. 2026; 19(1):260. https://doi.org/10.3390/en19010260

Chicago/Turabian Style

Adamczyk, Janusz, and Robert Dylewski. 2026. "Economic and Ecological Benefits of Thermal Modernization of Buildings Related to Financing from Aid Programs in Poland" Energies 19, no. 1: 260. https://doi.org/10.3390/en19010260

APA Style

Adamczyk, J., & Dylewski, R. (2026). Economic and Ecological Benefits of Thermal Modernization of Buildings Related to Financing from Aid Programs in Poland. Energies, 19(1), 260. https://doi.org/10.3390/en19010260

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