ASSESSMENT OF INFILTRATION AND TRANSMISSION HEAT LOSSES IN BUILDINGS
Reducing heat loss in buildings is a critically important task in the context of increasing energy efficiency and complying with modern environmental standards, particularly given the rising cost of energy resources. The aim of this study is comprehensive assessment of infiltration and transmission...
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| Дата: | 2025 |
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General Energy Institute of the National Academy of Sciences of Ukraine
2025
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Репозитарії
System Research in Energy| _version_ | 1871104430137409536 |
|---|---|
| author | Dekusha, Oleg Kovtun, Svitlana Antypov, Yevhen Gorobets, Valerii Tsapenko, Valentyn Riabikov, Artem |
| author_facet | Dekusha, Oleg Kovtun, Svitlana Antypov, Yevhen Gorobets, Valerii Tsapenko, Valentyn Riabikov, Artem |
| author_institution_txt_mv | [
{
"author": "Oleg Dekusha",
"institution": null
},
{
"author": "Svitlana Kovtun",
"institution": null
},
{
"author": "Yevhen Antypov",
"institution": null
},
{
"author": "Valerii Gorobets",
"institution": null
},
{
"author": "Valentyn Tsapenko",
"institution": null
},
{
"author": "Artem Riabikov",
"institution": null
}
] |
| author_sort | Dekusha, Oleg |
| baseUrl_str | https://systemre.org/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-18T12:57:50Z |
| description | Reducing heat loss in buildings is a critically important task in the context of increasing energy efficiency and complying with modern environmental standards, particularly given the rising cost of energy resources. The aim of this study is comprehensive assessment of infiltration and transmission heat losses, taking into account the influence of external factors and the structural features of buildings. To achieve this, numerical modeling of thermal processes, analytical calculations, and experimental methods were used, such as thermographic analysis and airtightness measurements. Based on the analysis of the obtained geometric parameters and thermophysical material properties, a calculation of heat losses through wall, window, and door structures was performed, specifically considering external factors such as wind speed, atmospheric pressure, and temperature differences. The study found that infiltration heat losses are highly dependent on the airtightness of the building envelope and can account for 10–15 % of total losses. The investigation of heat loss through windows confirmed the need to improve regulatory approaches for assessing their heat transfer. It was established that calculations based on current standards which affects up to 25 %, which affects the accuracy of energy audits. Transmission losses depend on the thermal resistance of the building envelope, and standard calculation methods can overestimate them by 17–51 %. It was found that with an increase in wind speed up to 20 m/s, heat losses grow by 20–30 %, which confirms the necessity of accounting for mixed convection regimes. Comparing the obtained experimental data with the calculation results allowed for the evaluation of errors in existing regulatory methods and the refinement of calculation approaches for determining heat losses. This study confirms the need to improve building heat loss assessment methods, considering the specific air permeability of materials. The results of this research can be used to improve methods for the energy analysis of buildings, develop more effective strategies for the thermal modernization of the building stock, and create scientifically-based recommendations for reducing energy consumption. |
| doi_str_mv | 10.15407/srenergy2025.04.094 |
| first_indexed | 2026-03-24T02:03:40Z |
| format | Article |
| fulltext |
Системні дослідження в енергетиці. 2025. 4(84) 94
ІНФОРМАЦІЙНО-ВИМІРЮВАЛЬНІ ТЕХНОЛОГІЇ,
МОНІТОРИНГ ТА ДІАГНОСТИКА В ЕНЕРГЕТИЦІ
_____________________________________________________________________________
ISSN 2786-7102 (Online), ISSN 2786-7633 (Print)
https://doi.org/10.15407/srenergy2025.04.094
UDC 536.2
Oleg Dekusha1,2, Dr. Sci. (Engin.), Senior Researcher, https://orcid.org/0000-0003-3836-0485
Svitlana Kovtun1, Dr. Sci. (Engin.), Senior Researcher, https://orcid.org/0000-0002-6596-3460
Yevhen Antypov3, Cand. Sc. (Eng.), https://orcid.org/0000-0003-0509-4109
Valerii Gorobets3, Dr. Sci. (Engin.), Professor, https://orcid.org/0000-0003-1180-4509
Valentyn Tsapenko1*, PhD (Engin.), https://orcid.org/0000-0003-1095-0117
Artem Riabikov1, https://orcid.org/0009-0003-6440-6202
1General Energy Institute of NAS of Ukraine, 172, Antonovycha St., Kyiv, 03150, Ukraine;
2Institute of Engineering Thermophysics of NAS of Ukraine, 2a, Marii Kapnist St., Kyiv,
03057, Ukraine;
3National University of Life and Environmental Sciences of Ukraine, 15, Heroiv Oborony St.,
Kyiv, 03041, Ukraine
*Corresponding author: capenko.valik@ukr.net
ASSESSMENT OF INFILTRATION AND TRANSMISSION HEAT LOSSES IN BUILDINGS
Abstract. Reducing heat loss in buildings is a critically important task in the context of increasing energy
efficiency and complying with modern environmental standards, particularly given the rising cost of
energy resources. The aim of this study is comprehensive assessment of infiltration and transmission heat
losses, taking into account the influence of external factors and the structural features of buildings. To
achieve this, numerical modeling of thermal processes, analytical calculations, and experimental methods
were used, such as thermographic analysis and airtightness measurements. Based on the analysis of the
obtained geometric parameters and thermophysical material properties, a calculation of heat losses
through wall, window, and door structures was performed, specifically considering external factors such
as wind speed, atmospheric pressure, and temperature differences. The study found that infiltration heat
losses are highly dependent on the airtightness of the building envelope and can account for 10–15 % of
total losses. The investigation of heat loss through windows confirmed the need to improve regulatory
approaches for assessing their heat transfer. It was established that calculations based on current
standards which affects up to 25 %, which affects the accuracy of energy audits. Transmission losses
depend on the thermal resistance of the building envelope, and standard calculation methods can
overestimate them by 17–51 %. It was found that with an increase in wind speed up to 20 m/s, heat losses
grow by 20–30 %, which confirms the necessity of accounting for mixed convection regimes. Comparing
the obtained experimental data with the calculation results allowed for the evaluation of errors in
existing regulatory methods and the refinement of calculation approaches for determining heat losses.
This study confirms the need to improve building heat loss assessment methods, considering the specific
air permeability of materials. The results of this research can be used to improve methods for the energy
analysis of buildings, develop more effective strategies for the thermal modernization of the building
stock, and create scientifically-based recommendations for reducing energy consumption.
Keywords: air permeability, energy efficiency, airtightness, building envelope, infiltration heat losses,
transmission heat losses, thermal imaging inspection.
1. Introduction
Ensuring energy efficiency in buildings is one of the key challenges in modern energy. A significant
portion of heat losses in buildings occurs due to infiltration and transmission processes, which substantially
impacts the level of energy resource consumption [1]. Optimizing the thermal protection of building
https://orcid.org/0000-0003-3836-0485
https://orcid.org/0000-0002-6596-3460
https://orcid.org/0000-0003-0509-4109
https://orcid.org/0000-0003-1180-4509
https://orcid.org/0000-0003-1095-0117
https://orcid.org/0009-0003-6440-6202
mailto:capenko.valik@ukr.net
Системні дослідження в енергетиці. 2025. 4(84) 95
structures and controlling air exchange play a decisive role in reducing energy costs, as well as improving
indoor environmental comfort [2].
Assessing infiltration and transmission heat losses allows to identify potential ways to improve
building energy efficiency by developing ways to minimize heat loss. Despite the wide range of existing
calculation methods and experimental studies, the issue of increasing the accuracy of determining heat flows
through building envelope and air leakages through the building's airtightness deficiencies remains relevant
[3].
Modern studies show that the influence of external factors, such as meteorological conditions, building
envelope materials, and peculiarities of ventilation systems, plays a significant role in heat loss processes [4].
Using innovative diagnostic methods such as thermographic analysis, numerical modeling, and the
application of wireless technologies allows for obtaining more accurate data on the characteristics of the
building envelope [1].
An analysis of literature sources on assessing heat losses in buildings demonstrates a wide range of
measurement approaches and methods for reducing energy consumption. Work [5] describes experimental
methods for determining infiltration losses, based on the use of aerometric studies and thermographic
analysis. Study [6] emphasizes the importance of considering meteorological conditions when assessing
transmission heat losses. Work [7] describes the methodology of thermographic surveys of residential
buildings, identifying the main areas of heat leakage, particularly through window and door units. Work [8]
investigates heat and moisture processes in building envelope structures, highlighting their influence on the
overall level of heat loss. The author examines the impact of changes in humidity and temperature on the
characteristics of building materials, concluding that seasonal fluctuations can lead to increased heat losses.
Study [9] conducted a comprehensive analysis of building heat losses using thermographic surveys,
confirming the effectiveness of this method in identifying areas of increased heat loss. Additionally, the
dependence of the heat transfer coefficient on wind speed was determined. In the study [10], the influence of
material air permeability on the overall level of heat loss was investigated. The authors concluded that
additional sealing of structures can reduce infiltration losses by 15−20 %. It is also worth noting that
regulatory documents, such as DSTU B V.2.6-23 [11], DSTU EN 14351-1 [12], and DSTU EN ISO 10077-1
[13], regulate approaches to calculating heat losses, but they have certain limitations that require further
clarification through experimental research.
The aim of this study is to assess infiltration and transmission heat losses in buildings using modern
numerical and experimental methods. This work specifically focuses on analyzing the impact of structural
features of building materials, the level of airtightness of the building envelope, and external factors (wind
flows, temperature differences) on heat transfer processes. The proposed approaches allow for improving
energy audit methods, increasing the accuracy of heat loss assessment, and developing effective measures for
the thermal modernization of buildings.
2. Methods and materials
In this study, a combination of numerical modeling and experimental methods was used to assess
infiltration and transmission heat losses in buildings. The main stages of the research were:
• analysis of room structural characteristics;
• heat loss calculation;
• modeling the influence of external factors;
• experimental studies;
• results evaluation.
Heat losses in residential and public buildings consist of heat losses through external structures (walls,
windows, floors, ceilings) and the heat consumed for warming air that infiltrates the premises through
airtightness deficiencies.
Infiltration and transmission heat losses are the two primary mechanisms of heat loss that impact a
building's energy efficiency. Infiltration heat losses are heat losses that occur due to the uncontrolled
Системні дослідження в енергетиці. 2025. 4(84) 96
penetration (infiltration) of cold air from the outside into the building's interior and the leakage of warm air
to the outside through cracks, gaps in windows and doors, construction joints, etc. These losses depend on
the building's airtightness level, wind speed, and the pressure and temperature differences between the
internal and external environments. Transmission heat losses through the building's building envelope (walls,
windows, doors, etc.) depend on the thermal resistance of the materials, the thickness of the structures, the
presence of thermal insulation, and the temperature difference between the internal and external
environments. Both types of heat losses significantly affect a building's energy consumption, and their
reduction is a key objective during thermal modernization and the design of energy-efficient structures [14].
In this study, the heat loss calculation was performed for an room in an academic building of the
National University of Life and Environmental Sciences of Ukraine. The lecture hall is located on the third
floor of a multi-story building. It measures 11.7 x 5.9 x 3.2 m and is situated in the end section of the
building, where two of its walls are external. The end wall of the room (5.9 m wide) is on the eastern side,
while the other wall (11.7 m wide) is on the southern side. The internal volume of the lecture hall is
V=220.9 m3.
The wall structure has the following layers: inner plaster – 0.02 m; solid clay brick masonry on
cement-sand mortar – 0.51 m; ceramic facing tile – 0.02 m; adhesive mortar layer – 0.01 m; mineral wool
insulation layer – 0.1 m; outer finish layer – 0.005 m. The room has four metal-plastic double-pane windows
measuring 2.1x2.2 m, for which the height from the floor level to the windowsill is 0.9 m (thermal resistance
of windows 0.6 m²·°C/W). The wooden door in the room measures 2.05x0.95 m and opens into the corridor
of the heated building's interior. The room is not equipped with an air ventilation system. Lighting is
provided by 40 fluorescent lamps, each with a power of 18 W (the conversion coefficient of electrical energy
to thermal for such lamp is 0.4). The room contains one computer (laptop) with a power of 60 W;
additionally, 25 people are simultaneously present in the room (under conditions of working with computer
equipment, the heat dissipation of one person is 125 W). The room also has four heating radiators with a total
power of 4.0 kW (1.0 kW each).
A calculation of the room's heat gains from lighting, occupants, household electrical appliances, and
solar radiation must be performed. The amount of heat emitted by lighting lamps can be found using the
formula:
𝑄𝑜𝑠 = 𝑛𝑙⸱𝑃𝑙⸱𝜂𝑙 = 288 W, (1)
where nl – number of fluorescent lamps in the room, pcs; 𝑃𝑙 – power of one lamp, W; 𝜂𝑙 – coefficient
indicating the proportion of power expended on heating the surrounding environment.
The amount of heat gain from people in the room can be calculated using the ratio:
𝑄𝑙𝑢𝑑 = 𝑛𝑙𝑢𝑑⸱𝑃𝑙𝑢𝑑 = 3125 W, (2)
where 𝑛𝑙𝑢𝑑 – the number of people in the room, persons; 𝑃𝑙𝑢𝑑 – the average value of the amount of heat
released by a person into the environment, W.
The amount of heat gain from household electrical appliances can be determined using the ratio:
𝑄𝑝𝑟𝑦𝑙 = ∑ 𝑃𝑖,𝑗⸱𝜂𝑖,𝑗 = 48 𝑊,𝑚
𝑖 (3)
where m – number of devices, pcs; 𝑃𝑖,𝑗 – electrical power of the source, W; 𝜂𝑖,𝑗 – coefficient indicating the
proportion of appliance power that is converted into thermal energy.
The amount of heat entering the room from solar radiation is determined as follows:
𝑄𝑣𝑦𝑝𝑟 = 𝑃𝑣𝑦𝑝𝑟⸱𝑛𝑣𝑘⸱𝐹𝑣𝑘⸱𝜂𝑝𝑟𝑜𝑝, (4)
Системні дослідження в енергетиці. 2025. 4(84) 97
where 𝑃𝑣𝑦𝑝𝑟 – the amount of thermal energy (incident from the Sun per 1 m2 of the object's surface when
windows are vertically positioned, which depends on the window's orientation relative to North, East, West,
South, the month of the year, and the geographical location of the settlement where the building is situated);
𝑛𝑣𝑘 – number of windows, pcs; 𝐹𝑣𝑘 – window surface area, m2; 𝜂𝑝𝑟𝑜𝑝 – coefficient of transmission of
thermal rays through the window surface, which depends on the type of window (single-chamber, double-
chamber, etc.), optical properties of glazing and other factors.
The calculation was performed according to the DSTU 9190 [15] methodology. In this room, the
windows are located on a wall structure with a southern orientation. The windows are made of transparent
glass. The thermal resistance through the windows, Qwin (according to DSTU B V.2.6-23 [11]), is in the
range of R=0.32−0.75 m2⋅°C/W, and the solar transmittance coefficient is in the range of τ=65−80 %. The
calculation was performed for January, for which the average monthly outdoor air temperature is minimal.
For one window (south-facing) 𝐹𝑣𝑘,1 = 2.1⸱2.2 = 4.62 m2, according to the recommendations given in
DSTU 9190:2022 [15] – 𝑃𝑣𝑦𝑝𝑟= 50 W/m2, 𝜂𝑝𝑟𝑜𝑝 = 0.675. Heat gains from solar radiation are calculated
using formula (4), resulting in 𝑄𝑣𝑦𝑝𝑟,1 = 144.375 W. Accordingly, for four south-facing windows, the heat
flow from solar radiation through the windows is: 𝑄𝑣𝑦𝑝𝑟,0 = 577.5 W.
When calculating the amount of heat entering the room from solar radiation, it's also necessary to
consider the shading reduction factor for movable devices – curtains, blinds [11]. In our case, colored textile
curtains are used for shading, for which, according to the DSTU standard [13], the reduction factor 𝜂𝑧ℎ can
range from 0.42 to 0.77. As a result, the total heat flow from solar radiation can be determined through
calculation.
𝑄𝑣𝑦𝑝𝑟 = 𝑄𝑣𝑦𝑝𝑟,0⸱𝜂𝑧ℎ = 346.5 W, (5)
a. Calculation of heat losses through the wall structure
The heat transfer coefficient through a multi-layered building wall is found from the ratio:
𝐾 =
1
1/𝛼𝑣𝑛+∑ 𝛿і/𝜆і+1/𝛼𝑧𝑜𝑣
𝑚
𝑖=1
, (6)
where 𝛼𝑣𝑛, 𝛼𝑧𝑜𝑣 – heat transfer coefficient on the inner and outer surfaces of the wall, W/m2⸱0С; 𝛿і -
thickness of the i-th layer of the wall, m; 𝜆і - thermal conductivity coefficient of the material from which the
i-th layer of the wall is made.
The heat exchange coefficient on the inner and outer surfaces of the wall under conditions of natural
convection 𝛼𝑣𝑛, 𝛼𝑧𝑜𝑣 is calculated based on experimentally determined temperature readings from the
internal and external sides of the room: the average temperature of the inner wall surface 𝑇𝑠𝑡1,𝑣𝑛 = 15 0С (for
the 11.7x3.2 m wall), 𝑇𝑠𝑡2,𝑣𝑛= 15 0С (for the 5.9x3.2 m wall), the air temperature in the room 𝑇𝑝𝑜𝑣,𝑣𝑛= 20 0С,
the average temperature on the outer wall surface 𝑇𝑠𝑡,𝑧𝑜𝑣= 5.2 0С, and the ambient air temperature 𝑇𝑝𝑜𝑣,𝑧𝑜𝑣=
5.4 0С. The heat transfer coefficient on the wall surfaces under natural convection conditions is found as
follows:
𝛼𝑣𝑛 = С0
𝜆𝑝𝑜𝑣,𝑣𝑛
𝐿
(𝐺𝑟𝐿 ⸱𝑃𝑟𝑝𝑜𝑣)𝑛, (7)
where 𝜆𝑝𝑜𝑣 𝑣𝑛 – thermal conductivity coefficient of air, W/m·°C; 𝑃𝑟𝑝𝑜𝑣 – Prandtl number for air; 𝐺𝑟𝐿 =
𝑔⸱𝛽⸱𝛥𝑇⸱𝐿3
𝜈2 – Grashof number, where 𝑔 = 9.8 m/s2 – gravitational constant, 𝛽 – coefficient of volumetric
thermal expansion of air, 𝛥𝑇 = Т𝑠𝑡 − Т𝑝𝑜𝑣 – temperature head on the wall surface, 0С, 𝜈 – kinematic
viscosity coefficient of air, m/s2; L – characteristic vertical dimension of the wall.
In the calculations, we will assume the values for the air parameters as follows:
Системні дослідження в енергетиці. 2025. 4(84) 98
1. At 20 0С: 𝜌𝑝𝑜𝑣 = 1.21 kg/m3, 𝜐𝑝𝑜𝑣 = 14.8⸱10−6 𝑚2/s, 𝜆𝑝𝑜𝑣 = 0.0256 W/m⸱K, Prpov=0.703, 𝛽
=0.0034;
2. At 5,4 0С: 𝜌𝑝𝑜𝑣 = 1.28 kg/m3, 𝜐𝑝𝑜𝑣 = 13.4⸱10−6 𝑚2/s, 𝜆𝑝𝑜𝑣 =. ,0246 W/m⸱K, Prpov = 0.707, 𝛽 =
0.0036.
We assume that the characteristic vertical dimension of the wall is L=3.2 m, the flow regime is
laminar, with С0 = 0.59; n=0.25. As a result of the calculations, we find the following for internal wall 1 and
wall 2: 𝛼𝑠𝑡,𝑣𝑛 = 1.82 W/(m2⸱K). The heat transfer coefficient on the outer surface of the walls is: 𝛼𝑠𝑡2,𝑣𝑛 =
0.834 W/(m2⸱K).
Considering the values of the thickness and thermal conductivity coefficient for each layer of the wall:
1 – plaster layer 𝛿1 = 0.02 m, 𝜆1 = 0.7 𝑊/m⸱K, 2 – solid clay brick masonry on cement-sand mortar layer
𝛿2 = 0.51 m, 𝜆2 = 0.81 W/m⸱K, 3 – ceramic facing tile layer 𝛿3 = 0.02 m, 𝜆3 = 3.49 W/m⸱K, 4 −
adhesive mortar layer 𝛿4 = 0.01 m, 𝜆4 = 0.87 W/m⸱K, 5 – mineral wool insulation layer 𝛿5 = 0.1 m, 𝜆5 =
0.05 W/m⸱K, 6 − outer finish layer 𝛿6 = 0.005 m, 𝜆6 = 0.87 𝑊/m⸱K.
We find the thermal resistance of the wall: ∑ 𝛿і/𝜆і
6
𝑖=1 = 2.93 m⸱
K
W
. Next, using formula (6), we find
the heat transfer coefficient through the wall, assuming only natural convection on the outer surface (no wind
flow present): 𝐾 =
1
1/𝛼𝑠𝑡,𝑣𝑛+∑ 𝛿і/𝜆і+1/𝛼𝑠𝑡,𝑧𝑜𝑣
𝑚
𝑖=1
= 0.214 W/m2⸱K.
The total surface area of the building walls bordering the external environment is found using the
formula: 𝐹𝑠𝑡 = 𝐹𝑠𝑡,𝑝𝑜𝑣 − 𝐹𝑣𝑘 = 37.84 m2, where 𝐹𝑠𝑡,𝑝𝑜𝑣 = 56.32 m2 – total area of two walls, 𝐹𝑣𝑘 =
18.48 m2.
We find the heat losses to the environment from the building's wall enclosures using the formula:
𝑄𝑠𝑡 = 𝐾⸱𝐹𝑠𝑡(𝑇𝑝𝑜𝑣,𝑣𝑛 − 𝑇𝑝𝑜𝑣,𝑧𝑜𝑣). (8)
We assume that 𝑇𝑝𝑜𝑣,𝑣𝑛 = 20 0С, 𝑇𝑝𝑜𝑣,𝑧𝑜𝑣 = −7. 40С are the internal temperature and the minimum
external air temperature during the cold period of the year. As a result of calculations using formula (8), we
obtain the heat loss value for wall surfaces (without considering wind flow) as 𝑄𝑠𝑡 = 221.64 W.
On the outer surface of the wall, there can be a mixed heat exchange regime with natural convection
(in the absence of wind) and forced convection (in the presence of wind flowing around the building). Wind
speed in Ukraine can vary in the range of 𝑊𝑤𝑖𝑡 = 0 − 20 m/s. For forced air flow, the heat transfer
coefficient on the wall surface is found using the formula:
𝛼𝑧𝑜𝑣,𝑣𝑚 = С1⸱
𝜆𝑝𝑜𝑣,𝑧𝑜𝑣
𝐿
⸱Re𝑍
𝑛⸱Pr𝑚, (9)
where 𝑅𝑒𝑍 =
𝑊𝑤𝑖𝑡⋅𝑍
𝜐𝑝𝑜𝑣
– Reynolds number, 𝜐𝑝𝑜𝑣 – coefficient of kinematic viscosity of air, m2/s; Z –
characteristic horizontal dimensions of the external wall in the direction of the wind, Pr – Prandtl number for
outdoor air, and coefficients C1 and exponents n and m depend on the Reynolds number 𝑅𝑒𝑍 and take the
following values:
• in the range 𝑅𝑒𝑍 ≤ 1010 С1 = 0.66; n = 0.5; m = 0.33;
• in the range 𝑅𝑒𝑍 ≥ 1010 С1 = 0.037; n = 0.8; m = 0.43.
When mixed convection is present, accounting for the combined contribution of natural and forced
convection on the external wall of the building, the heat transfer coefficient is calculated using the formula:
𝛼𝑧𝑜𝑣 = (𝛼𝑧𝑜𝑣,𝑝𝑟
3 + 𝛼𝑧𝑜𝑣,𝑣𝑚
3 )1/3. (10)
Системні дослідження в енергетиці. 2025. 4(84) 99
As the characteristic dimension of the wall for transverse wind flow, we will choose the average
transverse dimension of the room walls Z = 8.8 m. In calculations, we adopt the following air parameter
values at 7.4 0С: 𝜌𝑝𝑜𝑣 = 1.395 kg/m3, 𝜐𝑝𝑜𝑣 = 12.78⸱10−6 m2/s, 𝜆𝑝𝑜𝑣 = 0.0228 W/m⸱K, 𝑃𝑟𝑝𝑜𝑣 = 0.716.
Table 1 presents the results of calculating the Reynolds number, the heat transfer coefficient for
natural convection, and mixed convection on the external wall surface at various wind flow speeds, which
were calculated using formulas 6−10.
Table 1. Calculation of heat losses from wall structures at various airflow speeds
Air speed, m/s 0 1 5 10 15 20
Reynolds number 𝑅𝑒𝑍 588 760.875 2 943 806.6 58 875 112.1 8 831 419.87 11 775 227.6
Heat transfer
coefficient 𝛼𝑧𝑜𝑣,𝑣𝑚,
W/m2⸱𝐾
0.834 1.22 2.73 3.86 4.72 6.83
Heat transfer
coefficient 𝛼𝑧𝑜𝑣,
W/m2⸱𝐾
0.834 1.34 2.76 3.87 4.73 6.85
Overall heat transfer
coefficient К, W/m2⸱𝐾
0.214 0.237 0.26 0.268 0.271 0.276
Heat Loss
Magnitude 𝑄𝑠𝑡, W
221.64 245.73 269.57 277.87 280.98 286.16
For a comparative characteristic of the proposed approach, we will calculate the heat losses from the
wall structures of this room using the traditional method, which is outlined in DSTU 9191 [16]. According to
this standard, the following values for the heat transfer coefficients on the internal wall surfaces are used for
calculating heat losses through vertical wall structures 𝛼𝑠𝑡,𝑣𝑛 = 8.7 𝑊/(𝑚2⸱𝐾) and for the outer surface of
the wall 𝛼𝑠𝑡,𝑧𝑜𝑣 = 23 W/(m2⸱K) [17]. The heat transfer coefficient through a multi-layered wall is
calculated using formula (6), considering the thermal resistance of the wall, which consists of six layers: 𝐾 =
1
1/𝛼ст,𝑣𝑛+∑ 𝛿і/𝜆і+1/𝛼ст,𝑧𝑜𝑣
𝑚
𝑖=1
= 0.324 W/(m2⸱K). Using formula (8), we calculate the heat losses through the
wall structures of the room: 𝑄𝑠𝑡 = 334.48 W.
A comparison of these results with those obtained using the methodology proposed above (for which
heat losses 𝑄𝑠𝑡 are in the range of 221.64 W to 286.16 W depending on the airflow speed (see Table 1))
shows that using the current methodology according to DSTU 9190 [15] leads to an overestimation of heat
losses from wall structures by 17 %−51 %. This results in an increase in heating appliance capacity and
overconsumption of heat for heating the room [18, 19].
b. Calculation of heat losses through window structures
The coefficient of heat transfer through windows is found from the ratio:
𝐾 =
1
1/𝛼𝑣𝑘,𝑣𝑛+∑ 𝛿і/𝜆і+1/𝛼𝑣𝑘,𝑧𝑜𝑣
𝑚
𝑖=1
, (11)
where 𝛼𝑣𝑘,𝑣𝑛, 𝛼𝑣𝑘,𝑧𝑜𝑣 − heat transfer coefficients on the internal and external surfaces of the windows,
respectively, W/m2⸱0С; 𝛿і − thickness of the i-th window layer, m; 𝜆і − thermal conductivity coefficient of
the material of the i-th window layer.
For calculations, the values for the thermal resistance of windows can be used from the data provided
in DSTU B V.2.6-23 [11]. Specifically, this applies to single-chamber windows which consist of two glass
panes and one air gap ∑ 𝛿і/𝜆і
5
𝑖=1 = 0.5 m2⸱0С/W. The values for the heat transfer coefficients on the external
and internal surfaces of the windows, under conditions of natural convection (without wind flow), are
assumed in accordance with the requirements of Table B, Annex B of DSTU 9191 [16], respectively:
𝛼𝑣𝑘,𝑣𝑛 = 8 W/m2⸱K, 𝛼𝑣𝑘,𝑧𝑜𝑣 = 23 W/m2⸱K . From relation (11), we find: 𝐾𝑣𝑘 = 1.49 W/m2⸱K.
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A comparative calculation is performed according to the methodologies outlined in DSTU 9191 [16]
and DSTU EN ISO 10077-1 [13]. The thermal resistance of the window is determined by selecting a
combination of the transparent (glazing unit) and opaque (PVC profile, aluminum profile, or wooden
elements) parts of the window to meet the requirements: Rpr ≥ Rq min. The calculation of the equivalent
thermal resistance is performed according to DSTU EN ISO 10077-1 [13]. Based on the data:
− glazing area of the largest light-transmitting structure Ag = 4.62 m²;
− area of opaque infill Af = 1.16 m²;
− length of the glazing perimeter lg = 8.6 m;
− heat transfer coefficient of distance frames ψg = 0.06 m².
The equivalent thermal resistance of the entire window unit is:
𝑅𝑝𝑟 =
1
𝑈𝑤
. (12)
The heat transfer coefficient, Uw, of a single-glazed window is calculated according to
DSTU EN ISO 10077-1 [13]:
𝑈𝑤 =
∑ 𝐴𝑔∙𝑈𝑔+∑ 𝐴𝑓∙𝑈𝑓+∑ 𝑙𝑔∙𝜓𝑔
∑ 𝐴𝑔+∑ 𝐴𝑓
= 0.85
𝑊
𝑚2·𝐾
, (13)
where 𝑈𝑓 − heat transfer coefficient of the frame, which is determined in accordance with Annex D [13], 𝑈𝑓
= 1,2 W/(m2⸱K); 𝑈𝑔 − the heat transfer coefficient of the glazing unit is calculated using the formula,
W/(m2⸱K):
𝑈𝑔 =
1
𝑅𝑠𝑒+∑ 𝑗
𝑑𝑗
𝜆𝑗
+∑ 𝑗𝑅𝑠,𝑗+𝑅𝑠𝑖
= 0.79
𝑊
𝑚2·𝐾
, (14)
where 𝑅𝑠𝑒 − thermal resistance on the external side, m2·K/W; λj − thermal conductivity of the glass or
coating j, W/(m·K); dj − thickness of the glass or coating j, m; Rsi − thermal resistance of the glass from the
internal side, m2·K/W; Rs,j − thermal resistance of the j-th air gap is determined in accordance with
Annex C [13], m2·K/W. We compared the calculation results from formula (13) with the methodology
provided in the regulatory documents DSTU 9191 [16] and DSTU EN ISO 10077-1 [13]. The difference is
approximately 25 %, which is considered satisfactory. For subsequent calculations, we will use the results
obtained in accordance with the regulatory documents.
Heat losses through windows are calculated using the formula:
𝑄𝑣𝑘 = 𝑈𝑤⸱(𝐹𝑣𝑘,1 + 𝐹𝑣𝑘,2)⸱(𝑇𝑝𝑜𝑣,𝑣𝑛 − 𝑇𝑝𝑜𝑣,𝑧𝑜𝑣) = 592.43 W, (15)
where Fvk − total surface area of the windows in a, m2; 𝑇𝑝𝑜𝑣,𝑣𝑛, 𝑇𝑝𝑜𝑣,𝑧𝑜𝑣 − internal and external air
temperatures, respectively, 0С.
When wind flows are present, calculations are performed according to the methodology used for wall
structures. The average value of the transverse dimensions of the windows, Zvk = 2.2 m, was chosen as the
characteristic size for calculating the Reynolds number. The calculation results for various wind flow
velocities are presented in Table 2. It should be noted that the heat transfer coefficients for the outer glass
surface recommended in DSTU B V.2.6-23 [11] 𝛼𝑣𝑘,𝑧𝑜𝑣 = 23 W/m2 ⋅ K are overstated in the absence of
wind flow, since only the contribution of natural convection is taken into account.
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Table 2. Calculation of heat loss from window structures at different airflow velocities
Air speed, m/s 0 1 5 10 15 20
Reynolds number, 𝑅𝑒𝑍 196 487.5 982 437.01 1 964 873.99 2 947 311.0 3 929 747.7
Heat transfer
coefficient 𝛼𝑧𝑜𝑣,𝑣𝑚,
W/m2⸱𝐾
23* 2.667 5.964 8.43 10.04 11.92
Heat transfer
coefficient 𝛼𝑧𝑜𝑣,
W/m2⸱𝐾
23* 23.006 23.06 23.2 23.59 24.02
Heat transfer
coefficient К, W/m2⸱𝐾
1.17 1.18 1.19 1.21 1.26 1.31
Heat loss value 𝑄𝑣𝑘, W 592.43 699.07 823.99 837.34 872.46 907.08
*The numerical values of the heat transfer coefficient are provided according to the current methodology and the data from
Table B, Annex B of DSTU 9191 [16], which does not account for changes in airflow velocity.
Next, we will evaluate the heat transfer coefficient on the outer surface of the glass in the absence of
wind.
The calculation is performed using formula (6) with the following input parameters: 𝑇𝑣𝑘,𝑧𝑜𝑣 =
10.2 0С, 𝑇𝑝𝑜𝑣,𝑧𝑜𝑣 = 5. 20С - the outer glass surface temperature and the external air temperature,
respectively; L=2.1 m – typical vertical window size;
31.28 /pov mkg = ,
2613.4 1 /0pov m s −= ,
/0.0246пов m KW = , 0.707повPr = , 0.0036 = – thermophysical properties of the external air at
5.2 °C. As a result of the calculations, we get: 𝛼𝑣𝑘,𝑧𝑜𝑣 = 1.95
𝑊
𝑚2⸱𝐾
. The heat transfer coefficient is found
using formula (11): 𝐾𝑣𝑘 = 1.55 W/(m2⸱0С). The difference between the results obtained and the results
found according to the methodology of DSTU B V.2.6-23 [11] is approximately 25 %
As a conclusion, it can be stated that the current methodology of DSTU 9190 [15] provides a certain
error when calculating heat loss from window structures under external environmental conditions with low
wind flow velocities.
c. Calculation of heat loss due to air permeability
Heat loss through window air permeability is determined by the window's class. According to the
European standard EN 14351 [1], the air permeability class for a room is Class 4 (hermetic), which
corresponds to a value of 𝜂𝑝𝑜𝑣,𝑣𝑘= 3 m3/(m2·h) at a pressure of 100 Pa.
The airflow rate due to air permeability through windows, given a known pressure difference between
the room and the external environment, is typically determined by the following formula:
𝐺𝑣𝑘,𝑣 = 𝑛𝑣𝑘⸱𝐹𝑣𝑘⸱𝜂𝑝𝑜𝑣,𝑣𝑘(𝛥𝑃𝑝𝑜𝑣/100)/3600, (16)
where 𝐺𝑣𝑘,𝑣 – volumetric airflow rate through all the windows of the building, m2; 𝑛𝑣𝑘 – number of windows
in the building, pcs; 𝐹𝑣𝑘 − area of one window, m2; 𝜂𝑝𝑜𝑣,𝑣𝑘 − the specific air permeability for windows,
which is selected depending on the window class, m3/(m2·h); 𝛥𝑃𝑝𝑜𝑣 − pressure difference between the room
and the external environment.
The pressure difference is found using the formula:
𝛥𝑃𝑝𝑜𝑣 = 𝑔⸱ℎ𝑣𝑘⸱(𝜌𝑝𝑜𝑣,𝑣𝑛 − 𝜌𝑝𝑜𝑣,𝑧𝑛), (17)
where ℎ𝑣𝑘 − window height.
We calculate according to formula (17), 𝛥𝑃𝑝𝑜𝑣 = 3.35 Pa.
The airflow rate through the windows due to air permeability is calculated using formula (16): 𝐺𝑣𝑘,𝑣 =
0.000516 m3/s.
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The amount of heat loss due to window air permeability is found using the formula:
𝑄𝑖𝑛𝑓,𝑣𝑘 = 𝐺𝑣𝑘,𝑣⸱с𝑟,𝑝𝑜𝑣,𝑣𝑛⸱Т𝑝𝑜𝑣,𝑣𝑛, (18)
where с𝑟,𝑝𝑜𝑣,𝑣𝑛 − specific heat capacity of internal air, J/kg⸱0С; Т𝑝𝑜𝑣,𝑣𝑛 – its temperature, 0С.
The heat loss value due to window air permeability is found using formula (16) 𝑄𝑖𝑛𝑓,𝑣𝑘 = 0.0104 kW.
The amount of heat loss due to air permeability through walls, which consist of several layers of building
materials, depends on the air permeability coefficient of each layer and is calculated according to
DSTU-N B V.2.6.-191 [20].
The total value of the heat transmittance coefficient for a wall with n layers Gk is determined by the
formula:
𝐺к = (∑
1
𝐺𝑖
𝛥𝑃
𝑛
𝑖=1 )
−1
, (19)
where 𝐺𝑖
𝛥𝑃 − is the air permeability coefficient for the i-th layer.
The mass air permeability of a single-layer construction 𝐺к or an individual homogeneous layer of a
structure 𝐺 𝛥𝑃 is determined based on the pressure drop. This can be done either from the results of tests
carried out by accredited laboratories in accordance with DSTU-N B V.2.6.-191 [20], or by a formula:
𝐺к = 𝐺 𝛥𝑃 = 𝐺 𝛥𝑃0⸱(𝛥𝑝/𝛥𝑝0)𝑛, (20)
where 𝐺 𝛥𝑃0 – is the mass air permeability of the building envelope at 𝛥𝑝0, which is determined for specific
types of wall materials based on test results according to DSTU-N B V.2.6.-191 [20]; 𝛥𝑝0 – is the pressure
difference at which the mass air permeability of structures is determined experimentally (𝛥𝑝0=10 Pa); 𝛥𝑝 is
the calculated pressure difference, Pa; n is the filtration exponent, which is determined based on test results
according to DSTU-N B V.2.6.-191 [20]. For mineral wool insulation, n=1.5.
The calculated pressure difference is determined by the formula:
𝛥𝑝 = (𝐻 − ℎ𝑖)⸱(𝛾𝑧𝑜𝑣 − 𝛾𝑣𝑛) + 0,03⸱𝛾𝑧𝑜𝑣⸱𝑣2⸱𝛽𝑘, (21)
where 𝐻 − height of the building (from the first-floor level to the top of the exhaust shaft), m; ℎ𝑖 − height
from the first-floor level to the center of the building envelope of the i-th floor for which the calculation is
performed; 𝑣 − wind flow velocity, m/s; 𝛽𝑘 − coefficient for accounting for the velocity of external air
movement, depending on the building's height and the external conditions in which the building is located
(urban development with buildings over 25 m, etc.); 𝛾𝑧𝑜𝑣 , 𝛾𝑣𝑛 − specific weight of the external and internal
air, respectively, N/m³, which is calculated using the formulas:
𝛾𝑧𝑜𝑣 = 3463/(273 + 𝑡𝑧𝑜𝑣); 𝛾𝑣𝑛 = 3463/(273 + 𝑡𝑣𝑛). (22)
The coefficient for accounting for the velocity of external air movement, depending on the building's
height, is selected according to DSTU-N B V.2.6.-191 [20]. For a building up to 10 m high in a forested area,
we find that the coefficient is 𝛽к= 0.65.
We then proceed with the calculation of air permeability for the walls in the room. Using formula (22),
we find the specific weight of the external and internal air: 𝛾𝑧𝑜𝑣 = 13.8 N/m3, 𝛾𝑣𝑛 = 11.82 N/m3.
The pressure difference between the external and internal air is found in the absence of wind flow
(𝑣 = 0) using formula (21), considering the room is on the second floor, for which ℎ𝑖 = 4.8 m, 𝛥𝑝 =
3.168 Pa.
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Using formula (20) with these values 𝐺 𝛥𝑃0, we find the air permeability for each layer of the wall
structure:
for the 1st layer:
𝐺1
к = 𝐺1
𝛥𝑃 = 0.0048 kg/m3⸱h;
for the 2 st layer:
𝐺2
к = 𝐺2
𝛥𝑃 = 0.1 kg/m3⸱h;
for the 3st layer:
𝐺3
к = 𝐺3
𝛥𝑃 = 0.00048 kg/m3⸱h;
where 0.1 – is a coefficient that represents the percentage of sand-cement mortar located in the joint layer
between adjacent tiles where;
for the 4st layer:
𝐺4
к = 𝐺4
𝛥𝑃 = 0.0226 kg/m3⸱h;
for the 5st layer:
𝐺5
к = 𝐺5
𝛥𝑃 = 3.985 kg/m3⸱h;
for the 6st layer:
𝐺6
к = 𝐺6
𝛥𝑃 = 0.0226 kg/m3⸱h.
The total value of the air permeability coefficient for a 6-layer wall is determined using formula (19),
𝐺к = 0.000455 kg/(m³·h).
The heat loss through a building's enclosing wall structure can be determined using the formula.
𝑄𝑖𝑛𝑓,𝑠𝑡 = 𝐺к⸱𝐹𝑠𝑡⸱с𝑟,𝑝𝑜𝑣,𝑣𝑛⸱Т𝑝𝑜𝑣,𝑣𝑛⸱(𝛥𝑃𝑝𝑜𝑣/100)/3600, (23)
where 𝐹𝑠𝑡 − is the surface area of the entire building's enclosing wall structure, excluding the surface area of
windows and doors, in m²; с𝑟,𝑝𝑜𝑣,𝑣𝑛 − is the specific heat capacity of the indoor air, in J/(kg·°C); Т𝑝𝑜𝑣,𝑣𝑛 − is
its temperature, in 0С; 𝛥𝑃𝑝𝑜𝑣 − is the pressure loss, in Pa.
As a result of the calculations, we find the heat loss due to air permeability through the enclosing wall
structure of the room to be 𝑄𝑖𝑛𝑓,𝑠𝑡 = 3.05⸱10−6 kW.
In addition to the heat loss from air permeability through the wall structure, it is necessary to account
for the air permeability through the layer of foam sealant around the window structures. We calculate these
losses using a method similar to the one used for the wall structure. According to this method, we determine
the pressure difference between the indoor and outdoor air using formula (21) as 𝛥𝑝 = 3.168 Pa. Using
formula (20), and taking into account the values of 𝐺 𝛥𝑃0, we find the air permeability for the foam sealant
layer of the window structure to be 𝐺𝑝
𝐾 = 𝐺𝑝
𝛥𝑃 = 0.0048 kg/m3⸱h.
We determine the heat loss through the enclosing wall structure using formula (23), where 𝐹𝑝,𝑣𝑘 is the
surface area of the enclosing wall structure of the entire building, which is determined by the expression:
𝐹𝑝,𝑣𝑘 = 𝑛𝑣𝑘⸱𝑃𝑝⸱𝛥𝑙𝑝, (24)
where 𝑃𝑝 = 2(ℎ𝑣𝑘 + 𝑙𝑣𝑘) – is the external perimeter of the window; ℎ𝑣𝑘 , 𝑙𝑣𝑘 – are the height and width of the
window, 𝛥𝑙𝑝= 0.02 m – is the width of the mounting foam layer around the windows.
The calculation of heat loss due to air permeability through the polystyrene layer of mounting foam is
performed, resulting in 𝑄𝑖𝑛𝑓,𝑝 = 4.68⸱10−6 kW.
Heat loss due to the air permeability of enclosing structures has three components: losses through
window structures, wall structures, and the mounting foam layer around the windows. The total heat loss
through these components can be found using the following formula:
𝑄𝑖𝑛𝑓 = 𝑄𝑖𝑛𝑓,𝑣𝑘 + 𝑄𝑖𝑛𝑓,𝑠𝑡 + 𝑄𝑖𝑛𝑓,𝑝. (25)
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As a result of the calculations, we find the total losses due to air permeability to be: 𝑄𝑖𝑛𝑓 =
0.010408 kW.
In the presence of wind flow, it is necessary to account for additional pressure losses, which depend on
the wind speed v and a coefficient 𝛽𝑘, that considers the influence of the external environment. With a wind
speed of v =1 m/s and in the presence of a forest area (for which the coefficient 𝛽𝑘 is 0.65), the pressure
difference between the internal and external air is found using formula (21), 𝛥𝑝 = 3.44 Pa. The results of the
calculation regarding the influence of wind flow velocity on the air permeability of the multi-layer wall
structure are presented in Table 3.
Table 3. Heat loss due to air permeability from a multi-layer wall structure at different airflow velocities
Air speed, m/s. 0 1 5 10 15 20
Pressure difference
between the internal and
external environment,
Pa.
3.168 3.44 9.918 30.44
63.918
111.168
Air permeability
coefficient for a multi-
layer wall, kg/(m³·h).
0.000455 0.000515 0.00251 0.0135 0.0412 0.0947
Air permeability
coefficient for the
mounting foam layer,
kg/(m³·h).
0.0048 0.00486 0.00686 0.0178 0.0455 0.099
Heat loss through the
wall structure due to air
permeability, kW.
3.05⸱10-6 3.32⸱10-6 9.58⸱10-6 29.41⸱10-6 61.74⸱10-6 107.39⸱10-6
Heat loss through the
mounting foam layer
due to air permeability,
kW.
4.68⸱10-6 5.08⸱10-5 14.68⸱10-6 45.05⸱10-6 94.6⸱10-6 164.53⸱10-6
Total heat loss due to
air permeability Qinf, W.
1.0477 1.0484 1.0643 1.114 1.291 1.312
A comparative analysis of the results shows that the absence or presence of wind flow does not lead to
significant heat losses. This is due to the very small values of the air permeability coefficient. Under
conditions with or without wind flow in the range of 0-20 m/s, the air exchange rate in the room is within the
range of 0.61 to 0.74, depending on the wind speed.
3. Results and Discussion
A comparison of the calculated indicators with the results of experimental studies showed that the air
exchange rate in the experiments was close to 1.4 h⁻¹. This is due to the presence of non-airtight contact
points between casement windows and their frames, as well as between the ceiling slabs and external wall
structures, which were not taken into account when calculating ventilation losses.
However, the values obtained prove the previously stated assumption about the presence of hidden
ventilation openings in the room, which were not considered in the ventilation loss calculations and are not
accounted for by the current methodology.
Therefore, only the use of an improved heat loss calculation methodology for individual rooms of a
multi-story building — one that accounts for wind flow speeds in conjunction with an airtightness test of the
building envelope — will make it possible to realistically assess the actual level of energy consumption and
establish the building's energy efficiency class, as the difference between the obtained values can reach
40 %.
The heat balance of total heat losses and heat gains in the room is obtained by the formula:
Qbat=Qst+Qvik+Qdv+Qpid+Qst,sum+Qven+Qinf - Qos – Qpryl- Qlud- Qvypr (26)
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The presence of doors, floors, and walls that are adjacent to other rooms within the building does not
affect the heat losses and heat gains of the room. Therefore, given the absence of a ventilation system, we
can assume: Qdv=0, Qpid=0, Qst,sum=0, Qven=0.
By calculating all components of the heat losses and heat gains, we obtain the required heating load
for the room under no-wind conditions in the external environment, Qbat=-2991.88 W. In the absence of
people, Qbat=132.62 W.
In the presence of a wind flow that has different speeds, the results of calculating the total heat loss in
the room are given in Table 4.
Table 4. Total heat losses from the lecture room at different wind speeds
Airflow velocity, m/s. 0 1 5 10 15 20
Heat losses at different wind
speeds, without considering heat
gains Qbat , W.
-2992.38 -2861.65 -2712.88 -2691.18 -2653.75 -2612.95
Heat losses at different wind
speeds Qbat , W.
132.62 263.35 412.12 433.82 465.25 512.45
An analysis of the obtained data on heat losses from the lecture room shows that the required heating
power to heat this space and maintain a temperature of 20 °C, in the absence of occupants, is in the range of
132 W to 512 W, depending on the airflow velocity. Under conditions of people being present in the room
and during the operation of a mechanical supply and exhaust ventilation system, this value can be increased
by 1.5 times.
4. Conclusions
In the course of this study, infiltration and transmission heat losses of building structures were
evaluated. Modern methods for assessing heat loss were considered, including numerical modeling and
experimental studies using thermal imaging analysis. The obtained results allow for the following
conclusions.
Infiltration heat losses depend on the building's airtightness level and external factors such as wind
speed and pressure difference. The use of improved methodologies for calculating air permeability makes it
possible to reduce the error in determining heat losses and to adjust energy-saving measures.
Transmission heat losses are largely determined by the thermal resistance of the building envelope. A
comparative analysis of calculation methodologies showed that traditional regulatory approaches can
overestimate actual heat losses by 17−51 %, which may lead to excessive energy consumption for heating.
The influence of wind flows on heat transfer coefficients confirms the need to account for mixed
convection regimes when assessing heat losses through walls and window structures. Calculations showed
that with an increase in wind speed up to 20 m/s, heat losses can rise by 20−30 %.
The study of heat loss through windows confirmed the need to improve regulatory approaches to
evaluating their heat transfer. It was found that calculations based on current standards may contain an error
of up to 25 %, which affects the accuracy of energy audits.
The air permeability of the building envelope significantly affects the energy efficiency of buildings.
The analysis showed that heat loss through non-airtight structures can account for 10−15 % of a room's total
heat loss, and hidden ventilation openings, which are not considered by traditional methods, can increase the
air exchange rate.
The balance of heat losses and gains showed that the actual heating energy requirements for a room
can vary depending on the presence of wind flows and internal heat sources. To maintain a temperature of
20 °C, in the absence of occupants, the required heating power varies within the range of 132−512 W
depending on the airflow velocity.
Системні дослідження в енергетиці. 2025. 4(84) 106
The results obtained can be used for improving methods of building energy analysis, developing more
effective strategies for thermal modernization, and clarifying regulatory documents on the evaluation of
building heat loss.
Acknowledgment
These researches have been performed within the scientific program «Information technology for
energy audit of buildings as a component of the energy security of the country» (0123U103703, 2023-2024).
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ОЦІНКА ІНФІЛЬТРАЦІЙНИХ ТА ТРАНСМІСІЙНИХ
ТЕПЛОВТРАТ БУДІВЕЛЬ
Олег Декуша1,2, д-р техн. наук, ст. досл., https://orcid.org/0000-0003-3836-0485
Світлана Ковтун1, д-р техн. наук, ст. досл., https://orcid.org/0000-0002-6596-3460
Євген Антипов3, канд. техн. наук, https://orcid.org/0000-0003-0509-4109
Валерій Горобець3, д-р техн. наук, професор, https://orcid.org/0000-0003-1180-4509
Валентин Цапенко1*, д-р філософії, https://orcid.org/0000-0003-1095-0117
Артем Рябіков1, https://orcid.org/0009-0003-6440-6202
1Інститут загальної енергетики НАН України, вул. Антоновича, 172, Київ, 03150, Україна;
2Інститут технічної теплофізики НАН України, вул. Марії Капніст, 2а, Київ, 03057,
Україна;
3Національний університет біоресурсів і природокористування України, вул. Героїв
Оборони, 15, Київ, 03041, Україна
*Автор-кореспондент: capenko.valik@ukr.net
Анотація. Зменшення тепловтрат у будівлях є критично важливим завданням у контексті
підвищення енергоефективності та дотримання сучасних екологічних стандартів, особливо в
умовах зростання вартості енергоресурсів. Метою дослідження є комплексна оцінка
інфільтраційних та трансмісійних тепловтрат з урахуванням впливу зовнішніх факторів і
конструктивних особливостей будівель. Для досягнення поставленої мети застосовано чисельне
моделювання теплових процесів, аналітичні розрахунки та експериментальні методи, включаючи
тепловізійний аналіз та аерометричні вимірювання герметичності. На основі аналізу отриманих
геометричних параметрів та теплофізичних характеристик матеріалів проведено розрахунок
тепловтрат через стінові, віконні та дверні конструкції, зокрема з урахуванням таких зовнішніх
чинників як швидкість вітру, атмосферний тиск та температурні перепади. Результати
дослідження показали, що інфільтраційні тепловтрати значно залежать від рівня
герметичності огороджувальних конструкцій і можуть досягати 10–15 % від загальних втрат.
Дослідження теплових втрат через вікна підтвердило необхідність вдосконалення нормативних
підходів до оцінки їх теплопередачі. Встановлено, що розрахунки за чинними нормативами
можуть містити похибку до 25 %, що впливає на точність енергоаудиту. Трансмісійні втрати
також залежать від термічного опору огороджувальних конструкцій, а стандартні
розрахункові підходи можуть завищувати їх на 17–51 %. Виявлено, що зі збільшенням швидкості
вітру до 20 м/с тепловтрати зростають на 20–30 %, що підтверджує необхідність врахування
змішаних режимів конвекції. Порівняння отриманих експериментальних даних з результатами
розрахунків дозволило оцінити похибки існуючих нормативних методик та уточнити підходи до
розрахунків при визначенні теплових втрат. Це дослідження підтверджує необхідність
удосконалення підходів до оцінки теплових втрат будівель з врахуванням особливостей
повітропроникності матеріалів. Результати цього дослідження можуть бути використані для
вдосконалення методів енергетичного аналізу будівель, розробки більш ефективних стратегій
термомодернізації будівельного фонду, а також створення науково обґрунтованих рекомендацій
щодо зниження енергоспоживання.
Ключові слова: повітропроникність, енергоефективність, герметичність, огороджувальні
конструкції, інфільтраційні тепловтрати, трансмісійні тепловтрати, тепловізійне обстеження.
Надійшла до редколегії: 18.08.2025
https://orcid.org/0000-0003-3836-0485
https://orcid.org/0000-0002-6596-3460
https://orcid.org/0000-0003-0509-4109
https://orcid.org/0000-0003-1180-4509
https://orcid.org/0000-0003-1095-0117
https://orcid.org/0009-0003-6440-6202
mailto:capenko.valik@ukr.net
|
| id | systemreorg-article-927 |
| institution | System Research in Energy |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-19T01:23:58Z |
| publishDate | 2025 |
| publisher | General Energy Institute of the National Academy of Sciences of Ukraine |
| record_format | ojs |
| resource_txt_mv | systemreorg/79/335e66b479a75bc82560353336e29c79.pdf |
| spelling | systemreorg-article-9272026-07-18T12:57:50Z ASSESSMENT OF INFILTRATION AND TRANSMISSION HEAT LOSSES IN BUILDINGS Оцінка інфільтраційних та трансмісійних тепловтрат будівель Dekusha, Oleg Kovtun, Svitlana Antypov, Yevhen Gorobets, Valerii Tsapenko, Valentyn Riabikov, Artem air permeability, energy efficiency, airtightness, building envelope, infiltration heat losses, transmission heat losses, thermal imaging inspection. повітропроникність, енергоефективність, герметичність, огороджувальні конструкції, інфільтраційні тепловтрати, трансмісійні тепловтрати, тепловізійне обстеження. Reducing heat loss in buildings is a critically important task in the context of increasing energy efficiency and complying with modern environmental standards, particularly given the rising cost of energy resources. The aim of this study is comprehensive assessment of infiltration and transmission heat losses, taking into account the influence of external factors and the structural features of buildings. To achieve this, numerical modeling of thermal processes, analytical calculations, and experimental methods were used, such as thermographic analysis and airtightness measurements. Based on the analysis of the obtained geometric parameters and thermophysical material properties, a calculation of heat losses through wall, window, and door structures was performed, specifically considering external factors such as wind speed, atmospheric pressure, and temperature differences. The study found that infiltration heat losses are highly dependent on the airtightness of the building envelope and can account for 10–15 % of total losses. The investigation of heat loss through windows confirmed the need to improve regulatory approaches for assessing their heat transfer. It was established that calculations based on current standards which affects up to 25 %, which affects the accuracy of energy audits. Transmission losses depend on the thermal resistance of the building envelope, and standard calculation methods can overestimate them by 17–51 %. It was found that with an increase in wind speed up to 20 m/s, heat losses grow by 20–30 %, which confirms the necessity of accounting for mixed convection regimes. Comparing the obtained experimental data with the calculation results allowed for the evaluation of errors in existing regulatory methods and the refinement of calculation approaches for determining heat losses. This study confirms the need to improve building heat loss assessment methods, considering the specific air permeability of materials. The results of this research can be used to improve methods for the energy analysis of buildings, develop more effective strategies for the thermal modernization of the building stock, and create scientifically-based recommendations for reducing energy consumption. Зменшення тепловтрат у будівлях є критично важливим завданням у контексті підвищення енергоефективності та дотримання сучасних екологічних стандартів, особливо в умовах зростання вартості енергоресурсів. Метою дослідження є комплексна оцінка інфільтраційних та трансмісійних тепловтрат з урахуванням впливу зовнішніх факторів і конструктивних особливостей будівель. Для досягнення поставленої мети застосовано чисельне моделювання теплових процесів, аналітичні розрахунки та експериментальні методи, включаючи тепловізійний аналіз та аерометричні вимірювання герметичності. На основі аналізу отриманих геометричних параметрів та теплофізичних характеристик матеріалів проведено розрахунок тепловтрат через стінові, віконні та дверні конструкції, зокрема з урахуванням таких зовнішніх чинників як швидкість вітру, атмосферний тиск та температурні перепади. Результати дослідження показали, що інфільтраційні тепловтрати значно залежать від рівня герметичності огороджувальних конструкцій і можуть досягати 10–15 % від загальних втрат. Дослідження теплових втрат через вікна підтвердило необхідність вдосконалення нормативних підходів до оцінки їх теплопередачі. Встановлено, що розрахунки за чинними нормативами можуть містити похибку до 25 %, що впливає на точність енергоаудиту. Трансмісійні втрати також залежать від термічного опору огороджувальних конструкцій, а стандартні розрахункові підходи можуть завищувати їх на 17–51 %. Виявлено, що зі збільшенням швидкості вітру до 20 м/с тепловтрати зростають на 20–30 %, що підтверджує необхідність врахування змішаних режимів конвекції. Порівняння отриманих експериментальних даних з результатами розрахунків дозволило оцінити похибки існуючих нормативних методик та уточнити підходи до розрахунків при визначенні теплових втрат. Це дослідження підтверджує необхідність удосконалення підходів до оцінки теплових втрат будівель з врахуванням особливостей повітропроникності матеріалів. Результати цього дослідження можуть бути використані для вдосконалення методів енергетичного аналізу будівель, розробки більш ефективних стратегій термомодернізації будівельного фонду, а також створення науково обґрунтованих рекомендацій щодо зниження енергоспоживання. General Energy Institute of the National Academy of Sciences of Ukraine 2025-11-21 Article Article application/pdf https://systemre.org/index.php/journal/article/view/927 10.15407/srenergy2025.04.094 System Research in Energy; No. 4 (84) (2025): System Research in Energy; 94-107 Системні дослідження в енергетиці; № 4 (84) (2025): Системні дослідження в енергетиці; 94-107 2786-7102 2786-7633 en https://systemre.org/index.php/journal/article/view/927/825 Copyright (c) 2025 Oleg Dekusha, Svitlana Kovtun, Yevhen Antypov, Valerii Gorobets, Valentyn Tsapenko, Artem Riabikov https://creativecommons.org/publicdomain/zero/1.0 |
| spellingShingle | air permeability energy efficiency airtightness building envelope infiltration heat losses transmission heat losses thermal imaging inspection. Dekusha, Oleg Kovtun, Svitlana Antypov, Yevhen Gorobets, Valerii Tsapenko, Valentyn Riabikov, Artem ASSESSMENT OF INFILTRATION AND TRANSMISSION HEAT LOSSES IN BUILDINGS |
| title | ASSESSMENT OF INFILTRATION AND TRANSMISSION HEAT LOSSES IN BUILDINGS |
| title_alt | Оцінка інфільтраційних та трансмісійних тепловтрат будівель |
| title_full | ASSESSMENT OF INFILTRATION AND TRANSMISSION HEAT LOSSES IN BUILDINGS |
| title_fullStr | ASSESSMENT OF INFILTRATION AND TRANSMISSION HEAT LOSSES IN BUILDINGS |
| title_full_unstemmed | ASSESSMENT OF INFILTRATION AND TRANSMISSION HEAT LOSSES IN BUILDINGS |
| title_short | ASSESSMENT OF INFILTRATION AND TRANSMISSION HEAT LOSSES IN BUILDINGS |
| title_sort | assessment of infiltration and transmission heat losses in buildings |
| topic | air permeability energy efficiency airtightness building envelope infiltration heat losses transmission heat losses thermal imaging inspection. |
| topic_facet | air permeability energy efficiency airtightness building envelope infiltration heat losses transmission heat losses thermal imaging inspection. повітропроникність енергоефективність герметичність огороджувальні конструкції інфільтраційні тепловтрати трансмісійні тепловтрати тепловізійне обстеження. |
| url | https://systemre.org/index.php/journal/article/view/927 |
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