Insulation
More than half of the heat loss from a house or apartment in winter occurs through windows. With energy prices constantly rising, replacing outdated windows with efficient, practical plastic frames is the solution to the problem. Comfort and the level of spending on heating and air conditioning depend on the choice.
Types of glass
Double-glazed windows
The central element of the window. Double-glazed windows make up 90% of the area - 2 - 3 sheets, parallel inserted into a metal frame made of aluminum or stainless steel. The structure is sealed with butyl and filled under pressure above atmospheric with dried air and inert gas. A granular water vapor absorber is placed inside the frame to prevent fogging.
If the internal fogging of the glass unit occurs when the temperature changes, this means a breakdown. Air penetrates inside and increases heat loss.
Double-glazed window functions:
- Thermal insulation. It is carried out due to the absence of air circulation inside (as in a traditional wooden window), filling with dried or inert gas, and the use of materials with the finest coating that reflect thermal radiation, reducing heat loss.
The heat-saving efficiency coefficient of a plastic window (PVC profile) is equal to the heat loss of a brick wall about a meter thick!
- Noise insulation. It is carried out by two chambers filled with gas with a density different from atmospheric air. The distance between the walls of the chambers is 1.5-2 times greater than usual. The dimensions of the first gap on the street side exceed the second. Effective absorption and reflection of sound waves is achieved while reducing heat loss.
- Sun protection. It is carried out by coating with a film, spraying substances (metals or plastic). The amount of transmitted light flux decreases. It is possible to apply sun protection coating in different colors - green, gray, bronze. The tinting can be made dense; the windows on the street side will have a mirror surface.
- Anti-vandal. This includes protection from window damage, including protection from bullets. This is done by applying an armor film and making a triplex window. The cost of such double-glazed windows is higher than other options, and the weight of the structure increases. It is important to consider when installing in windows on balconies and loggias.
What should the area of the windows be?
Obviously, the larger the area of the window opening, the more heat can leave the room through it. But you can’t do without windows at all... The area of the windows should be justified by calculation: why did you choose this particular width and height of the window?
Hence the question: what is the optimal window area in residential buildings?
If we turn to GOSTs, we will get a clear answer:
The area of the window opening must provide a coefficient of natural illumination (KEO), the value of which depends on the construction area, the nature of the terrain, orientation to the cardinal points, the purpose of the room, and the type of window frames.
It is believed that enough light enters the room if the total area of all glass surfaces is 10...12% of the total area of the room (calculated by floor). According to physiological indications, it is believed that the optimal lighting condition is achieved with a window width equal to 55% of the width of the room. For boiler rooms, the light opening area is 0.33 m2 per 1 m3 of room volume.
Individual premises (for example, boiler rooms) have their own requirements, which you need to learn about in the relevant regulatory documents.
Glass unit marking
Each certified product is marked. It contains information about the type, thickness, space between sheets, number of chambers, gas composition, level of heat loss.
In Russia, two labeling standards are used - international (for imported products) and GOST (domestic production).
International marking:
- For single-chamber - “XX—X—XX”
- For two-chamber - “XX—X—XX—X—XX”
Instead of the letter "X" the following is used:
- Grade, sheet thickness are indicated as in the table below
- Type of gas inside the package
Gas filling
- The size of the internal chambers - indicated by numbers, can range from 0.6 to 3.6 cm
GOST marking:
- SP - abbreviation for package
- O and D - single-chamber and two-chamber SP
UD, E, S, M, Sh - shock-resistant, energy-saving, sun-protective, frost-resistant, noise-proof.
The types of material used are designated as follows:
Types of glass according to GOST
The role of a PVC profile window in the thermal protection of a room
Today, most of the enterprises involved in the production of plastic windows and doors use a 3-chamber profile (from various manufacturers) and a double-glazed window (hereinafter referred to as s/p) (4M—10—4M—10-4M). According to GOST 30674-99 “Window blocks made of polyvinyl chloride profiles”, the heat transfer resistance of a window structure made of a 3-chamber profile with a two-chamber s/p 4M-10-4M-10-4M (the most common and frequently used s/p) is 0. 51 (m2•°C)/W.
The value is a reference value, but in reality the values for these structures vary within the range of 0.53-0.56 (m2•°C)/W. In what ways is it possible to increase the heat transfer resistance of plastic windows to at least today’s 0.6 (m2•°C)/W, not to mention the rapid obsolescence of construction requirements and taking into account the 20-40 year life of the window, without significantly increasing the cost of the entire window designs?
On November 23, 2009, the Federal Law on Energy Saving and Increasing Energy Efficiency (No. 261-FZ) was adopted. It is expected that this law will help create the legal, economic and organizational framework for stimulating energy conservation and increasing energy efficiency. It will also affect the installation of window systems. But first things first.
On May 1, 2010, an order was adopted that approves energy efficiency requirements for buildings, structures, and structures. The updated law requires replacing windows with energy-efficient ones (with a reduced heat transfer resistance of 0.56-0.8 (m2•°C)/W). The legislator allocated his own period for this: from 2011 to 2015. To put it in simple and understandable language, over the next four years windows should become 48% warmer.
Requirements for windows will apply not only to municipal institutions and housing under construction, but also to already built houses. The requirements for installing energy consumption meters will push us towards this. According to preliminary estimates, from January 1, 2011, Russians who have not installed a meter will overpay for water, gas and heat almost double, and from 2012 - even fourfold.
This incentive practice is widespread in Western Europe, where owners of houses without meters pay for utility bills at rates several times higher.
Inspired by the prospects, we will understand: plastic windows consist of two main elements: PVC profiles (frame, sash, impost, glazing beads, etc.) and s/p. It is these components that determine the heat transfer resistance value of the entire window structure.
Chamber width (sound insulation)
An important function of the window is noise protection. The maximum permissible sound intensity for a person during the day is 40 dB, at night - 30 dB. A busy city street is noisy at 80-90 dB. The need for protection from excess noise is obvious.
This is done by thickening one of the glasses (outer), increasing the internal space. There can be two chambers in a double-glazed window.
Structurally, for effective sound insulation, they often use (mm):
- Single-chamber: internal 4 - space 16 - external 6
- Two-chamber: room 4 - space 10 - middle 4 - space 10 - external 6
- Two-chamber: internal 4 - cavity 10 - middle 4 - cavity 16 - external 6
- Two-chamber: indoor 4 - gap 16 - middle 4 - gap 6 - external 6
Comparative characteristics of common types of glass for windows
In addition to the number of chambers, sizes, and thickness of the sheets in the package, materials that protect against heat loss can be used - “triplex” - a sandwich of two tempered glasses, between which a film is laid. A design option with a decorative appearance is to use three films as the “filling” of the sandwich - two reinforcing films, one colored.
Installing a plastic window with a standard package reduces the noise level by 25-35 dB and heat loss by several times.
Windows can reduce street noise up to 3-5 times. Before installation, you need to measure the noise level at the location of the window, carry out comparative calculations, and select a design.
Triplex glass unit
Thermal conductive heat transfer
This heat transfer is inherent in solid materials. The cause of heat loss in this case is the “cold bridge”. The “cold bridge” means a spacer frame made of aluminum located inside the glass unit. Professionals from Modern-XXI proposed a simple and effective solution - to use the “warm” polymer distance Super Spacer. Tests have shown that the temperature level on the inside of the glass unit has increased, which significantly reduces the likelihood of condensation. Thus, mold and mildew caused by dampness, which can be dangerous for children and adults prone to allergic reactions, do not appear on the frame.
In addition, to reduce heat loss and increase the thermal resistance of a metal-plastic structure, qualified specialists suggest using profile structures with heat-insulating inserts in the air chambers.
If we consider wooden structures, it is recommended to use a larger beam, or a special beam with a thermal insert. The characteristics of such timber in terms of heat retention are significantly higher than those of standard Euro timber. Also, timber with a thermal insert does not bear any load on the fittings. The following comparison can be given as an example. A pine beam 13.8 cm thick will have the same resistance to heat transfer as a timber with a thermal insert, but 7.8 cm wide.
Energy saving glass
To reduce heat transfer through infrared radiation, energy-saving glasses have been developed. They are often called heat-saving, selective, low-emission. This means low thermal conductivity and protection against heat loss.
Tinted glass for window
Quality is achieved by using high-quality sheets cast into horizontal molds for production. Compared to those pulled vertically from the melt, they are more optically pure, homogeneous, and transparent. After polishing, the sheet is placed in a chamber where a thin layer of metal oxide and polymer compounds are applied. Based on the differences in manufacturing nuances, types with “hard” and “soft” coatings are distinguished.
Impact resistant glass for window
K - glass (hard coating)
The hard-coated material is called K-glass. Developed first, more expensive to produce. The metal layer is applied during casting of the sheet. Tin compounds are used. The advantage of the material is protection against heat loss, high mechanical strength, and resistance of the metal inclusion to wear. Can be used in single-chamber packages.
Installation of 1-chamber and 2-chamber double-glazed windows
I—glass (soft coating)
It has a greater degree of heat loss reduction and is cheaper. The downside is the low strength of the coating (silver compounds, complex organic polymers). The material is used in two-chamber bags. Placed in the middle of the structure. I-glass is more common than its counterpart, K-glass.
Soundproof glass for window
Heat loss
Heat can leave a room for three reasons:
- Infrared radiation of the room, environment
- Convection of internal gases
- Thermal conductivity of glass, window frames
A high-quality, sealed profile and properly installed window frames may be useless for reducing heat loss if a low-quality, large-area double-glazed window is installed in them.
Energy saving glass for windows
Heat loss calculation
Having received the initial data, designers begin calculations. Let's consider the main types of heat losses and formulas for their calculation. There are heat losses: through walls, through the floor, through windows, through the roof, through ventilation shafts and additional heat losses. Thermal resistance for all structures is calculated using the formula
Rst =1/ αв+Σ(δі / λі)+1/ αн,
where αв is the heat transfer coefficient of the inner surface of the fence, W/m2 °C; λi and δi – thermal conductivity coefficient for the material of each layer of the wall and the thickness of this layer in m; αн – heat transfer coefficient of the outer surface of the fence, W/m2·os;
Coefficients α are taken from the standards, and are different for walls and ceilings.
So, let's begin:
First of all, let's look at heat loss through the walls
The design of the walls has the greatest influence on them. Calculated using the formula: Coef. n-correction factor. Depends on the material of the structures, and n=1 is accepted if the structures are made of piece materials, and n=0.9 for the attic, n=0.75 for the basement floor.
Example: Let's consider heat loss through a 510 mm brick wall with 100 mm mineral wool insulation and a 30 mm decorative finishing ball. Internal air temperature 22ºС, external -20ºС. Let it be 3 m high and 4 m long. The room has one external wall, placement to the South, the area is not windy, without external doors. First you need to know the thermal conductivity coefficients of these materials. From the table above we find out: λk =0.58 W/mºC, λut =0.064 W/mºC, λsht =0.76 W/mºC. After this, the thermal resistance of the enclosing structure is calculated:
Rst=1/ 23 +0.51/0.58+0.1/0.064+0.03/0.76+ 1/ 8.6 = 2.64 m2 ºС/W.
For our area, such resistance is not enough and the house needs to be better insulated. But that’s not about that now. Heat loss calculation:
Q=1/R·FΔt·n·β=1/2.64·12·42·1·(10/100+1)=210W.
ß is additional heat loss. Next, we will describe their meaning and it will become clear where the number 10 comes from and why divide by 100.
Next comes heat loss through the windows
Everything is simpler here. Calculation of thermal resistance is not necessary, because it is already indicated in the passport of modern windows. Heat loss through windows is calculated according to the same scheme as through walls. For example, let's calculate the losses through energy-saving windows with a thermal resistance of Ro = 0.87 (m2°C/W) of size 1.5 * 1.5 and oriented to the North. Q=1/0.87·2.25·42·1·(15/100+1)=125 W.
Heat loss through ceilings includes heat removal through roof and floor coverings. This is mainly done for apartments where both the floor and ceiling are reinforced concrete slabs. On the top floor only losses through the ceiling are taken into account, and on the first floor only through the basement floor. This is due to the fact that the same air temperature is assumed in all apartments, and heat transfer from apartment to apartment is not taken into account. Recent studies have shown that large heat losses occur through non-insulated junctions between floors and enclosing structures.
The definition of heat leakage through a ceiling is the same as for a wall, but additional heat loss is not taken into account. The coefficient α is taken differently: α in = 8.7 W/(m 2 K) α in = 6 W/(m 2 K), the temperature difference is also the same, because in the basement or in a covered attic the temperature is taken within 4-6ºС. We will not describe the calculation of thermal resistance for the ceiling, because it is determined by the same formula Rst = 1/ αв + Σ ( δі / λі ) + 1/ α. Let's take a ceiling with a resistance of 4.95 and take the air in the attic +4ºС, the ceiling area is 3x4 m, inside 22ºС. Substitute into the formula and get: Q=1/R·FΔt·n·β=1/4.95·12·18·0.9= 40 W.
Calculation of heat loss through the floor on the ground
It is a little more complicated than through the ceiling. Heat losses are calculated by zone. A zone is a strip of floor 2 m wide, parallel to the outer wall. The first zone is located directly next to the wall, where the most heat loss occurs. It will be followed by the second and other zones, up to the center of the floor. For each zone, its own heat transfer coefficient is calculated. To simplify, the concept of resistivity is introduced: for the first zone R1=2.15 (m2°C/W), for the second R2=4.3 (m2°C/W), for the third R3=8.6 (m2°C/W) W)
Example There is a room in which the floor is on the ground, the floor size is 6x8 m. The temperatures are still the same. First, let's divide the floor into zones. We got two of them. Find the area of each zone. For us it is 20 m2 for the first zone and 8 m2 for the second. Then we set the conditional resistances R1=2.15 (m2°C/W), R2=4.3 (m2°C/W), substitute into the formula: Q=(F1/R1+F2/R2+F3/R3)( tout - tin) n=(20/2.15+8/4.3) 42 1= 470 W.
Additional heat loss
They are taken into account only for walls and windows, that is, structures that are in direct contact with the environment. There are four types of additional heat loss: orientation, windiness, the number of walls and the presence of external doors. They are expressed as a percentage and subsequently converted into an additional heat loss coefficient. If the room is oriented to the North, East, North-East, North-West, additional heat loss is 10%, when to the South, West, South-West, South-East, 5% is added. If the building is located in a windy area, another 10% of heat loss is added, and when in an area protected from the winds, only 5%. If the room has two external walls, then additional losses are 5%, when there is only one, there are no additional losses. If there is a door in the external wall, you can calculate the loss through it, but it is easier to add 60% if the doors are triple, 80% if the doors are double and 95% if they are single. For example: A room has two external walls, located in a windy area, one wall faces South, the other faces North, there are no doors. Then the additional losses are 10% + 5% for orientation + 10% for wind + 5% since there are two walls. And that 30%, in order to add them to the main heat losses, needs to be converted into a coefficient β = 30% + 100% = 30/100 + 1 = 1.3 and substituted into the general formula.
Heat loss for ventilation
They are not taken into account if air heating is being designed or a ventilation unit with air heating is used, since the air entering the room is already warm and no heat is wasted on heating it. But if the installation is not heated, it is necessary to take into account the heat consumption for heating the incoming air. The simplified formula looks like this:
Q=0.337·V·Δt
where V is the room in m3, Δt is the difference between external and external temperatures.
The sum of all heat losses constitutes the total losses of the room.
Thermal radiation and glass selection
At least 65% of heat loss through glass occurs due to thermal (infrared) radiation. The correct type of glass for the package will help reduce heat loss. The most effective way is to use energy-saving glass. Thanks to the coating with metal oxides, they reflect most of the infrared radiation.
Increasing the thickness of the glass in the package does not bring any benefit; the weight of the window and cost increase. The use of energy-saving material and window profiles allows you to save up to 30% on heating costs. The downside is the high price, but it will quickly pay for itself if you calculate it.
Energy saving windows
Simple methods that require minimal costs
Let's look at the simplest ways to reduce heat loss in a room. They, as you can guess from the name, will not require large expenses.
Install a foil (heat-reflecting) screen near the battery . Thanks to this, thermal energy will be reflected and directed into the room, and not spent on heating the wall.
Reflective screen behind the battery
Close doors/windows . The easiest way to save heat is to simply close doors and windows tightly.
Close windows and doors
Insulation of doors/windows . If the windows are wooden, then you need to seal the areas where the glass is adjacent to the frame. To reduce heat loss, simply cover the cracks or install seals.
Window sealing
Eliminate window shading . Up to 95 percent of sunlight passes through the window, and therefore heat will accumulate inside the room. This is confirmed by the fact that many greenhouses are made of glass.
Solar radiation
Solar radiation is the flow of energy emitted by the sun. Consists of visible and invisible radiation. Important invisible components are ultraviolet and infrared radiation. The first has bactericidal properties, causes a tan, the second - heat, for example, like from a kettle with hot water, heat transfer from a heating radiator.
SP is kept indoors, and up to 60% of infrared radiation is not allowed from the street. Heat loss from rooms in winter and overheating in summer are reduced. Reduced heating and air conditioning costs.
Glass in old wooden frames absorbs ultraviolet radiation. Double-glazed windows transmit a safe amount of radiation. Helps cleanse rooms from pathogenic microscopic organisms and spores.
Where does the heat leave the house?
The walls are insulated, the ceiling and floor too, the shutters are installed on five-chamber double-glazed windows, the gas boiler is fired up with all its might. But the house is still cool. Where does the heat continue to go from the house?
Now is the time to look for cracks, crevices and crevices where heat is escaping from your home.
Firstly, the ventilation system. Cold air enters the house through the supply ventilation, and warm air leaves the house through the exhaust ventilation. To reduce heat loss through ventilation, you can install a recuperator - a heat exchanger that takes heat from the outgoing warm air and heats the incoming cold air.
Secondly, the entrance doors. To prevent heat loss through the doors, a cold vestibule should be installed, which will act as a buffer between the entrance doors and the street air. The vestibule should be relatively sealed and unheated.
