Thermal insulation (thermal protection)
Thermal insulation is one of the main functions of a window, which provides comfortable conditions indoors.
The heat loss of a room is determined by two factors:
- Transmission losses, which consist of heat flows that the room gives off through walls, windows, doors, ceiling and floor.
- Ventilation losses, by which we mean the amount of heat required to heat the cold air entering through window leaks and as a result of ventilation to room temperature.
In Russia, to assess the heat-protective characteristics of structures, it is accepted heat transfer resistance R o(m² · °C/W), the reciprocal of the thermal conductivity coefficient k, which is accepted in DIN standards.
Thermal conductivity coefficient k characterizes the amount of heat in watts (W) that passes through 1 m² of structure with a temperature difference on both sides of one degree on the Kelvin scale (K), unit of measurement W/m² K. Than less value k, the less heat transfer through the structure, i.e. its insulating properties are higher.
Unfortunately, a simple recalculation k V R o(k=1/R o) is not entirely correct due to differences in measurement techniques in Russia and other countries. However, if the product is certified, then the manufacturer is obliged to provide the customer with the heat transfer resistance indicator.
The main factors influencing the value of the reduced heat transfer resistance of a window are:
- window size (including the ratio of the glazing area to the area of the window block);
- cross section of frame and sash;
- window block material;
- type of glazing (including the width of the remote frame of the double-glazed window, the presence of selective glass and special gas in the double-glazed window);
- number and location of seals in the frame/sash system.
From the indicator values R o The temperature of the surface of the enclosing structure facing the interior of the room also depends. When there is a large temperature difference, heat is radiated towards the cold surface.
Poor thermal insulation properties of windows inevitably lead to the appearance of cold radiation in the window area and the possibility of condensation on the windows themselves or in the area where they adjoin other structures. Moreover, this can happen not only as a result of low heat transfer resistance of the window structure, but also due to poor sealing of the joints of the frame and sash.
The heat transfer resistance of enclosing structures is standardized SNiP II-3-79*"Construction Heat Engineering", which is a reissue SNiP II-3-79“Construction Heat Engineering” with amendments approved and put into effect on July 1, 1989 by Decree of the USSR State Construction Committee dated December 12, 1985 241, amendment 3, put into effect on September 1, 1995 by Decree of the Ministry of Construction of Russia dated August 11, 1995. 18-81 and amendment 4, approved by Resolution of the State Construction Committee of Russia dated January 19, 1998 18-8 and put into effect on March 1, 1998.
In accordance with this document, when designing, the reduced heat transfer resistance of windows and balcony doors R o should be taken no less than the required values, R o tr(see table 1).
Table 1. Reduced heat transfer resistance of windows and balcony doors
| Buildings and constructions | Degree-day heating season, °C day | The reduced heat transfer resistance of windows and balcony doors is not less than R negative, m² · °C/W |
|---|---|---|
| Residential, medical and preventive care and children's institutions, schools, boarding schools | 2000 4000 6000 8000 10000 12000 |
0,30 0,45 0,60 0,70 0,75 0,80 |
| Public, except for those listed above, administrative and domestic, with the exception of rooms with humidity or wet conditions | 2000 4000 6000 8000 10000 12000 |
0,30 0,40 0,50 0,60 0,70 0,80 |
| Industrial with dry and normal mode | 2000 4000 6000 8000 10000 12000 |
0,25 0,30 0,35 0,40 0,45 0,50 |
| Note: 1. Intermediate values R neg should be determined by interpolation 2. Standards for heat transfer resistance of translucent enclosing structures for premises industrial buildings with a humid or wet regime, with excess sensible heat from 23 W/m 3, as well as for premises in public, administrative and domestic buildings with a humid or wet regime should be taken as for premises with a dry and normal regime of industrial buildings. 3. The reduced heat transfer resistance of the blind part of balcony doors must be no less than 1.5 times higher than the heat transfer resistance of the translucent part of these products. 4. In certain justified cases related to specific constructive solutions filling window and other openings, it is allowed to use designs of windows, balcony doors and lanterns with a reduced heat transfer resistance 5% lower than that specified in the table. |
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Degree-days of the heating season(GSOP) should be determined by the formula:
GSOP = (t in - t from.trans.) · z from.trans.
Where
t in- design temperature of internal air, °C (according to GOST 12.1.005-88 and design standards for relevant buildings and structures);
t from.trans.- average temperature of the period with average daily air temperature below or equal to 8°C; °C;
z from.trans.- duration of the period with an average daily air temperature below or equal to 8°C, Days (according to SNiP 2.01.01-82"Building climatology and geophysics").
By SNiP 2.08.01-89* when calculating enclosing structures residential buildings should be taken: internal air temperature 18 °C in areas with the coldest five-day temperature (determined according to SNiP 2.01.01-82) above -31°C and 20°C at -31°C and below; relative humidity air equal to 55%.
Table 2. Outdoor temperature(selectively, fully see SNiP 2.01.01-82)
| City | Outside air temperature, °C | ||||
|---|---|---|---|---|---|
| The coldest five days | Period with average daily air temperature ≤8°C |
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| 0,98 | 0,92 | Duration, days. | average temperature, °С | ||
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Vladivostok |
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Volgograd |
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Krasnoyarsk |
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Krasnodar |
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Murmansk |
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Novgorod |
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Novosibirsk |
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Orenburg |
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Rostov-on-Don |
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Saint Petersburg |
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Stavropol |
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Khabarovsk |
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Chelyabinsk |
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To facilitate the work of designers in SNiP II-3-79*, the appendix also contains a reference table containing the reduced heat transfer resistances of windows, balcony doors and lanterns for various designs. It is necessary to use this data if the values R not in the standards or technical conditions on the structure. (see note to table 3)
Table 3. Reduced heat transfer resistance of windows, balcony doors and skylights(informative)
| Filling the light opening | Reduced heat transfer resistance Rо, m² °С/W | ||
|---|---|---|---|
| in wooden or PVC bindings | in aluminum covers | ||
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1. Double glazing in paired frames |
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2. Double glazing in separate frames |
0,34* |
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3. Hollow glass blocks (with joints 6 mm wide) size, mm: |
0.31 (without binding) |
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4. Box section profile glass |
0.31 (without binding) |
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5. Double plexiglass for skylights |
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6. Triple plexiglass for skylights |
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7. Triple glazing in separate-pair bindings |
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| 8. Single-chamber glass unit: Ordinary |
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9. Double-glazed window from glass: Normal (with an interglass distance of 6 mm) Normal (with an interglass distance of 12 mm) With hard selective coating With soft selective coating |
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10. Regular glass and single-chamber double-glazed windows in separate glass frames: Ordinary With hard selective coating With soft selective coating With selective hard coating and argon filled |
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| 11. Ordinary glass and double-glazed windows in separate glass frames: Ordinary With hard selective coating With soft selective coating With selective hard coating and argon filled |
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| 12. Two single-chamber double-glazed windows in paired frames | |||
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13. Two single-chamber double-glazed windows in separate frames |
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14. Four-layer glazing in two paired frames |
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| *Bound in steel Notes:
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In addition to all-Russian regulatory documents, there are also local ones, in which certain requirements for a given region can be tightened.
For example, according to Moscow city building regulations MGSN 2.01-94"Energy supply in buildings. Standards for thermal protection, heat and water power supply.", reduced heat transfer resistance (R o) must be at least 0.55 m²·°C/W for windows and balcony doors (0.48 m²·°C/W is allowed in the case of using double-glazed windows with heat-reflecting coatings).
The same document contains other clarifications. To improve the thermal protection of the fillings of light openings in the cold and transitional periods of the year without increasing the number of layers of glazing, the use of glasses with selective coating should be used, placing them on the warm side. All door frames of windows and balcony doors must contain sealing gaskets made of silicone materials or frost-resistant rubber.
Speaking about thermal insulation, it is necessary to remember that in summer windows should do the opposite. winter conditions function: protect the room from penetration solar heat to a cooler room.
It should also be taken into account that blinds, shutters, etc. work as temporary heat protection devices and significantly reduce heat transfer through windows.
Table 4. Thermal transmittance coefficients of solar shading devices
(SNiP II-3-79*, Appendix 8)
|
Sun protection devices |
Thermal transmittance coefficient |
|---|---|
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A. External
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0,15 |
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Note:
1. Thermal transmittance coefficients are given as a fraction: before the line - for sun protection devices with plates at an angle of 45°, after the line - at an angle of 90° to the plane of the opening. 2. The thermal transmittance coefficients of inter-glass solar shading devices with a ventilated inter-glass space should be taken as 2 times less. |
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Modern double-glazed windows are presented in a wide variety both on the domestic and global markets. These are extremely popular devices, with the help of which you can always improve the internal climate in a house or apartment, no matter what condition it is in. High quality modern double glazed windows in the window openings of your home is a guarantee that in the summer you will not swelter from the heat, and in the winter the rooms of your home will always be warm. It is obvious that a comfortable temperature in the rooms directly affects the mood of the residents. Another quite significant advantage of double-glazed windows is that thanks to them, it becomes possible to significantly save on energy bills, reducing resource costs for air conditioning and heating at home. Glazing is effective solution to create comfort in the home
The most important property
The heat transfer resistance of a double-glazed window is, without a doubt, the most significant property of the structure. As is known, the system always strives to achieve homogeneity in all components. Thus, the thermal balance between the outside world and the premises of the building is the most ordinary physics, which is simply impossible to cope with. However, modern specialists have been able to significantly extend the time period during which the process of achieving thermal balance between external environment and areas of the building. There are different categories of metal-plastic window structures. 
Experts take the so-called heat transfer resistance coefficient of a double-glazed window as the basis for the classification. It is determined by the amount of heat that, in two environments with a temperature difference of exactly one degree Kelvin, passes through one square meter surfaces. This definition is recorded in the relevant state standard and is mandatory for Russian Federation. Thanks to the calculation of this parameter, we are able to judge the heat-protective characteristics of various construction projects in general and double-glazed windows in particular.
What is the essence of this parameter?
It is quite obvious that the thermal conductivity of metal-plastic window structures is a decisive parameter, on which not only the scope of application of the product directly depends, but also its popularity in the domestic and world markets. Thus, this property qualitatively illustrates what the thermal insulation characteristics of a structure are in reality. So, for example, a small value of this coefficient means that the object has proportionally small heat transfer. Thus, heat loss through this design will be insignificant, which means the object itself can be characterized as a structure with high thermal insulation parameters. 
Meanwhile, a simplified recalculation of this coefficient cannot be considered truly correct. Unfortunately, specialists in the Russian Federation use absolutely different systems calculations of this parameter, which often contradict each other. In addition, foreign specialists in the construction industry use counting systems regulated by their legislation. However, if the product has passed all stages of the necessary certification, then the manufacturer openly presents to potential buyers the thermal insulation properties of specific products.
For convenience, the heat transfer resistance of double-glazed windows for the main categories of double-glazed windows is shown in the table below: 
Select products by class
Of course, the technical terminology is completely foreign to ordinary consumers. In order to potential clients manufacturers of double-glazed windows were not confused by the wide variety of products offered; a system was introduced to divide these products into certain classes. In general, a division of goods into ten classes is proposed, the last of which is the best:
Meanwhile, even this distribution is not very informative for the average buyer. It is quite difficult for the average consumer to figure out which class of products will optimally fit into specific operational and climatic conditions. Government organizations are given and alternative options dividing products in this segment into categories. So, the system that offers to choose a package based on the duration is quite understandable. heating season and temperature differences between outside and inside premises. 
Technical parameters of structures
It is quite logical that the thermal resistance of a structure largely depends on the number of cameras installed in it. It is important to understand that it is the number of cameras that influences, and not the thickness of each individual glass. To summarize, it must be said that those double-glazed windows that are equipped big amount chambers will have much higher heat retention rates.
To the credit of modern product manufacturers in this market segment, their products have fairly high performance in all respects. Thanks to modern technologies Manufacturers have the opportunity not only to design structures with the optimal number of chambers, but also to fill the inter-chamber space with gaseous substances, which have a positive effect on the overall technical and operational characteristics of the products. The chambers are filled with a variety of inert gases, and low-emission coatings are specially applied to their surface. 
Glazing is an effective design solution
It is worth noting that today’s most successful manufacturing companies of translucent window structures increase the thermal insulation properties of their products largely through the use of technological process specific techniques. This, for example, could be coatings with energy-saving, sun-protection and magnetron properties, as well as providing high level sealing chambers, etc. 
The most popular trends in manufacturing
The production of double-chamber double-glazed windows has far ceased to be the limit for modern companies. Thus, products in this market segment, through the common efforts of global manufacturers, are being improved more and more every day. IN in this case We are talking not only about changes in schemes and design specifics, but also about the introduction of ultra-modern production technologies. In addition, among the innovative developments are the so-called selective glasses, which in turn are classified according to the type of coating into the following types:
- K-glass, which is characterized by a hard coating;
- I-glass, which, accordingly, has a soft coating.
Due to the specific characteristics of I-glasses, today they are the most in demand both in the domestic market of manufacturers and among potential buyers. The thermal conductivity of such glasses is completely insignificant. Thus, the thermal insulation performance of these products is much higher. They are almost one and a half times superior to their K-analogs. Verified information is provided by domestic statisticians, who claim that it is double-glazed windows, which are based on I-glass, that are most in demand in our country. In addition, their popularity is constantly growing both in the Russian Federation and far beyond its borders. 
Due to potential consumers, as a rule, constantly live in conditions of limited time, it is simply pointless to spend precious free minutes on a not very exciting choice of double-glazed windows. Therefore, experts offer several tips that will allow you to quickly and successfully select the optimal product:
- First of all, you need to understand that in residential premises it is worth installing structures with a heat transfer resistance of 0.45. The glass unit shown in this case is the minimum of those that comply with modern domestic building codes.
- If you plan to glaze premises such as an apartment or a private house outside the city, then two-chamber structures would be the best option. You should not try to save on glazing of residential premises, because the most affordable option in terms of price - single-chamber products - will not provide warmth and comfort in the premises.
Double-glazed window - best option for home - In the process of selecting the optimal double-glazed window, you should not forget about what PVC profile it will be installed in. The fact is that different manufacturers often offer different options profile systems. In this regard, not every double-glazed window can be mounted in the profile you like.
- Qualified and experienced craftsmen, who have been working on glazing for many years various rooms, called energy-saving products with two chambers practically ideal solution for the average buyer. It is these designs that can provide sufficient comfort and optimal temperature regime inside the living quarters.
- Please note the possibility of installing a spacer frame, which has low thermal conductivity. Its installation, in turn, involves the use of a technique known as “warm edge”. Due to this technology, the likelihood of condensation formation is minimized, since in the edge segment window design the temperature rises.
- If it is important for you that the window also has enhanced sound insulation properties, you need to choose glass with a large thickness or pay attention to window systems, in which a combination of glasses with different thicknesses is implemented.
Thanks to expert advice and the desire to make your home warm and cozy, you will quickly select the double-glazed window you need. It is enough just to study the theory of the issue a little and not refuse the help of professionals. 
Heat transfer in building envelopes is a complex process involving convection, conduction and radiation. All of them occur together with the predominance of one of them. Thermal insulation properties fencing structures that reflect heat transfer resistance must comply with current building codes.
How does heat exchange between air and enclosing structures?
In construction they ask regulatory requirements to the amount of heat flow through the wall and through it, its thickness is determined. One of the parameters for its calculation is the temperature difference between outside and inside the room. The coldest time of the year is taken as a basis. Another parameter is the heat transfer coefficient K - the amount of heat transferred in 1 s through an area of 1 m2, with a difference in temperature of the external and internal environment of 1 ºС. The value of K depends on the properties of the material. As it decreases, the heat-insulating properties of the wall increase. In addition, the cold will penetrate less into the room if the thickness of the fence is greater.
Convection and radiation from outside and inside also affect heat loss from the house. Therefore, reflective screens are installed on the walls behind the batteries. aluminum foil. Similar protection is also done inside ventilated facades from the outside.
From the article you will learn:
Long gone are the days when a person’s home was without a window. As is known from, at first an opening was used to communicate with the outside world small size. With the development of technology and skills, the window opening has adopted standard sizes - those that are used in our time.
Today in the doorway, apart from a small percentage wooden windows sample of the Soviet era, it is customary to insert windows modern type: plastic, aluminum, or wood with double-glazed windows. Let's take a closer look at the first type - light-transmitting products, the basis of which is (polyvinyl chloride).
The design of plastic windows, execution, as well as the quality of installation determine their harmony with the interior of the room, the safety of people in it, convenience, and - this is known to everyone. However, how to choose a high-quality plastic window, what thermal conductivity criteria should it meet? This is what this article will discuss.
On today's Russian market window designs presented wide range models. Almost each has its own characteristics and characteristics. Therefore, it is no wonder that it is not so easy for the average buyer to figure out which window is better. In this case, it would be better to follow individual requirements, presented to future design. At the same time, one of the main ones is compliance with climatic conditions, in which it is planned to use a plastic window.
It's true - windows designed for use in homes southern region, due to their thermal conductivity qualities, are not suitable for use in the northern part of our country. And vice versa.
So what is the thermal conductivity of a window and how does its value affect the retention of heat in a room? Let's start with a definition.
Window thermal conductivity value.
The thermal conductivity of plastic windows is called the ability closed window keep a certain amount of heat in the room. To denote this ability of a window structure, it is customary to use the term “ coefficient of thermal conductivity" The smaller it is, the more windows keep warm.
What affects the thermal conductivity of plastic windows? The main technical element that directly affects the thermal conductivity value is intimate glass unit. The fact is that there is a certain dependence: with an increase in the number of chambers, the thermal conductivity of a plastic window decreases, and this, in turn, has a positive effect on the amount of heat retained in the room by the window structure.
Table.
To make it easier to navigate thermal conductivity different models windows, use the table showing glazing methods and thermal conductivity coefficient various types windows We remind you that the lower the coefficient, the better.
| Glazing method | Thermal conductivity coefficient for wooden, combined and PVC windows | Thermal conductivity coefficient for aluminum and steel windows |
| Single pane window | 6,2 | |
| Double glass window | ||
| Triple glazing with two 12 mm air gaps | ||
| Double glazing with an air gap of 2 to 4 cm | ||
| Double glazing (4 mm glass and 12 mm air gap) | ||
| Triple glazing (4 mm glass plus two 12 mm air layers) |
The data presented in the table clearly indicate that for northern regions Russia for glazing window openings it is better to use, since it is precisely such designs that allow the most in full preserve the existing heat in the house.
In areas with a warm climate, installation of double-glazed windows will most likely be sufficient, in terms of price-performance ratio.
Of course, on comfortable temperature indoors is also influenced by the fact whether there were plastic windows installed in accordance with GOST. After all, it's of poor quality PVC installation products can negate the entire thermal conductivity advantage of any window model.
In addition to heat retention, plastic windows have another important characteristic, without which the comfort of being indoors modern conditions would hardly be possible. It's about, of course, about . With today's large concentration of cars on the roads, the noise they produce can reach 60-80 dB, which, with prolonged exposure to a person's hearing, can cause discomfort and irritability.
Heat loss through window glass consist of radiation losses (IR radiation), transmission losses (thermal conductivity of air, glass and structural elements) and convective heat losses due to air movement in the inter-glass space. Accordingly, the heat transfer resistance of a double-glazed window is influenced by the number and thickness of glass, the distance between the glass, the composition of the gas in the space between the glass, the presence of special low-emissivity glass, and the design of the spacer frames. For heat transfer resistance window profile influence: the thickness of the wooden profile and the type of wood, thickness and design internal chambers PVC profile, design of “thermal breaks” in aluminum profiles.
Often when choosing windows, there are such misconceptions about the heat transfer resistance of windows.
Myth 1. It is necessary to choose windows with the maximum value of heat transfer resistance
In fact, this is not true. Unlike walls, through which heat is only lost in winter, windows are a translucent structure. During the heating season, heat is both lost and gained through windows due to solar radiation. An increase in the heat transfer resistance of double-glazed windows is achieved mainly through the use of low-emissivity glass, which reduces light transmission. Therefore, the resulting energy efficiency of windows during the cold period of the year must be assessed comprehensively, taking into account all factors.
Thus, in one of the works of MGSU specialists it is shown that for the conditions of Moscow, the optimal heat transfer resistance value is 0.6 m2x deg/W, and not 0.8 and then 1.0, which officials talk about. In addition, we must not forget that the MAIN purpose of the window is natural lighting of the premises, characterized by the value of KEO (natural illumination coefficient). To maintain the required level of illumination when using double-glazed windows with multiple panes or using low-emissivity glass, it is necessary to increase the glazing area, and this will lead to increased heat loss, since the windows still remain several times cooler than the wall.
The solution in this situation is the following: when choosing windows for a newly constructed building or for re-glazing an old one, it is necessary to make a DESIGN of translucent structures that takes into account all these factors - heat loss and gain for a specific object, conditions for meeting the requirements for insolation and natural light.
Myth 2. Often there is a requirement like “for climatic conditions city N is required to use windows with a heat transfer resistance of at least, for example, 0.65 m2. x deg/W"
To put it mildly, in such cases the numbers are “pulled out of thin air.” Yes, in regulatory documents minimally specified valid values resistance to heat transfer of windows depending on the value of GSOP (degree-days of the heating period), characterizing the severity of the climate of a given area. But it's not that simple. In this area in residential buildings old building there are a lot of old wooden windows with Rpr. = 0.4 m2 x deg./W and people live there peacefully at normal temperature. In cold weather -30 degrees in this city in passenger cars With one glass, you can safely drive in just a shirt. It's only a matter of the heating power of the car or apartment.
Windows are not chosen for an apartment with some kind of constant heating to keep it warm in winter, but the heating system is calculated by the designer for certain windows. For a long time There were no modern sealed windows in Russia. There was wooden “joinery” of the OS and OR series (windows with paired and windows with separate sashes), respectively, with a heat transfer resistance of 0.4 and 0.44 m2 x deg./W. And the heating system of buildings was designed specifically for such windows.
Therefore, it makes sense to comply with the requirements of the standards for linking the heat transfer resistance of windows to GSOP when replacing windows in old housing stock only in houses built after 2000. In older houses, it is enough to install windows similar in this parameter to the old ones. This is subject to normal design heating. If there is “under-heating”, of course, it is necessary to install warmer windows with the reservations given above in point No. 1.