Frequently Asked Questions

Questions about double glazing energy glass

From what factors depends the depreciation in money I will have from replacing my windows?

Quenching money for replacing frames entails energy savings and depends on many factors. Some of them are:

• The amount of energy used for heating or cooling consumption
• The price of oil and electricity
• The square meters of the building and the glass panes to be placed
• The type of energy glass pane
• The kind of welding and the materials to be used for bending the glass pane etc
• The type of spacer (spacer)

Is it enough to replace the old windows of my house with "Energy windows" to ensure substantial energy savings?

First of all, it is vital to know that each building is the composition of many elements, such as the roof, the frames, the walls, the floor. The heat of a building escapes from everywhere. For this reason, the replacement of glass panes is necessary because:

  1. Replacement of glass panes is simple and quick
  2. From the frames of a building, it escapes up to 30% (approximately) of its heat
  3. This replacement has a relatively low cost and is more advantageous than other interventions
  4. The results are immediate and the benefits visible

All types of double glazing are also energy windows?

Absolutely not. Thermal insulation performance of energy glazing is not comparable to conventional double-glazing. In other words, energy savings are only achieved with energy double and triple glazing. For example, the difference between an energy glazing and a common double glazing is as huge as the difference between a common double with a single glazing. It is also necessary to make it clear that all energy glass panes are not identical to each other, so they do not all have the same technical specifications and characteristics.

Why should I put energy glasses in my house?

If we analyze the responsibilities of the structural elements in the heat dissipation in an average house we realize that:

• 20% of heat loss is due to the roof
• 25% of the thermal loss is due to the walls
• 20% of the heat loss is due to the floor
• 35% of heat loss is due to windows

Summing up all the above, we can easily conclude that the easiest, the most economical, the most ecological but also the most efficient way to reduce heat loss and consequently save money is achieved by installing energy glass panes.

Energy glass:

• Reflects the infrared sunlight (heat)
• Acts as a shield against indirect heat from the surrounding area
• Has more efficient thermal insulation in the winter
• It is easier to cool in the summer
• Significantly reduces annual heating and cooling costs
• Contributes substantially to the protection of the environment
• Reduces up to 70% incoming ultraviolet radiation (depending on the type of glass pane)
• It has a minimal cost difference from common double glazing

What does “Four Seasons Energy Glass” mean?

The classification of energy glasses in “Two Seasons” and “Four Seasons” is a misconception that divides. In fact, the energy glass has technical specifications that characterize it and compare it to other types of glasses, so that it can finally be decided, if it is more appropriate than another. In analyzing the technical specifications of an energy glazing we consider factors such as U-value value, light transmission and light reflection, solar energy transmission and solar energy reflection and solar factor. For example, an energy glazing can have a good coefficient of light transmission, while another has a better coefficient of energy transmission than the first one. The consumer in the process of selecting energy glazing must assess the type of glass he will eventually place based on his geographical area and assess the needs of his home / working place. In conclusion, it is these factors that characterize each energy glass separately and not its classification as “Two or Four Seasons Glass”.

How is the Declaration of Performance and what do its coefficients and values express?

file_pdf_download-128

DECLARATION OF PERFOMANCE

 

U value is a measure of the insulation capacity. In other words, the ability of a material to act as a thermal “barrier” between indoor and outdoor air.

Ug = coefficient of thermal conductivity of a double glazing unit 

Uf = coefficient of thermal conductivity of a window frame

Uw = coefficient of thermal conductivity of a window system

Actually, Ug indicates the sum of the energy we need to consume in order to maintain a temperature difference between the spaces separating the materials. The lower this value is, the more efficient the glazing is and so, the less watt has to be consumed.

LightTransmission and Light Reflection: these factors are directly related to the climate in which the double glazing unit will be installed. Moreover, they depend on the needs and requirements of the building.

Energy Transmission and Energy Reflection: these factors are also directly related to the climate in which the double glazing unit will be installed. Moreover, they depend on the needs and requirements of the building.

Solar Factor: is the percentage of solar energy passing through a space from the double glazing. The lower this value is, the less solar energy passes inside the space.

What can I do to improve the thermal insulation of my glass panes?

There are 3 ways to improve the glazing of your house/working place etc.

  • Use energy double or triple glazing
  • Increase as much as possible the space of the glass up to 16mm.
  • Use noble gas such as argon instead of normal air in the gap space of the glass pane.
  • Place swisspacer or stainless steel spacer
  • Apply: 1st step with butyl sealant and 2nd step with cool sealant (thiocol)

 


file_pdf_download-128

DECLARATION OF PERFORMANCE

The appropriate size of the spacer is 16mm. Below this size, the double glazing performance is quite low.

(the smaller the Ug-value the more efficient the double glazing) 

 

 


 

file_pdf_download-128

DECLARATION OF PERFORMANCE

The appropriate size of the spacer is 16mm. If this size increases, the double glazing performance will either remain constant or decreased.    

(the smaller Ug-value the more efficient the double glazing)

 


 

file_pdf_download-128

DECLARATION OF PERFORMANCE

 

Argon instead of Air, in the double glazing unit, improves U-value and therefore it significantly enhances its performance.

(the smaller the U-value the more efficient the double glazing)

 


 

file_pdf_download-128

DECLARATION OF PERFORMANCE

Ug variance = 1,6
(the smaller Ug-value the more efficient the glazing)

LightTransmission and Light Reflection: these factors are directly related to the climate in which the double glazing unit will be installed. Moreover, they depend on the needs and requirements of the building.

Solar energy transmission: In winter we need heat in our space, while in summer we prefer the opposite. Therefore the coefficient should be as small as possible.

Solar energy reflection: this coefficient should be as large as possible.

Therefore, double glazing with energy glass panes (low-e) significantly surpasses double glazing with common glass panes .

Solar  Factor variance = 39
Solar Factor: is the percentage of solar energy passing through a space from the  glazing. The lower this value is, the less solar energy passes inside the space.
(The lower the price the less solar energy transfered into the interior).

Why do glass panes get moisture?

First of all, it is important to clarify that the moisture inside the double glazing unit is an extremely different phenomenon than the moisture appeared on the frames’ surfaces and thus the glazing. Thermal losses in a frame depend on four factors:

A. the material of the frame

B. the type of the glass panes

C. the percentage of frame’s coverage in the frame and

D. the length of the thermal bridge formed at the point where the glazing joins the frame

 

More specifically, regarding the glass, the phenomenon of moisture on glazing and generally in window frames occurs in four cases.

Assuming that we have a window with a  double glazing unit, for example 4mm – 16mm – 4mm

  • In position 1 or outside position of the first pane to the outside environment,
  • In position 2 or inner position of the first pane inside the gap,
  • In position 3 or outside of the second pane inside the gap,
  • In position 4 or the inner side of the second pane to the inside environment of the space.

 

Condensation in the inner position (position 4) usually starts from the corners, as a result of the strong cooling, created by the existence of the thermal bridge. The surface moisture on the outside position of the glass (position 1) rarely starts at the corners, once the edges of the outside glass pane are usually warmed and the coolest point on the outside of the pane is usually located in its central region.
However, it is necessary to note that over time the persistent condensation becomes a fertile place for the growth of mold and bacteria. Mold can get into the air we breathe, aggravate breathing conditions or cause other health problems.

Why the spacer in the double glazing unit is so important?

pacers are responsible for the distance between the panes of a window. However, the quality of the spacers depends on the conductivity “λ” or otherwise the thermal conductivity of the material from which they are made. The conductivity “λ” of a material indicates the thermal power or heat – expressed in watt (W) – which penetrates a layer of 1m thickness material over 1h if the material surface is 1m² and there is a temperature difference between the original of the final side 1 Kelvin (= 1 ° C).

Conductivity is important because it shows us if the material has thermal insulation capabilities or not and how much. At this point, let us clarify that the lower the value, the better the material used on the frame. To make this easier to understand, the following table shows the conductivity factors for various materials.

Material Thermal conductivity (W/mK)
Aluminum 160
Stainless steel 15-17
Swisspacer 0.16

What forms of humidity we can encounter in a double glazing unit?

Condensation in Position 1

The moisture effect on the exterior surface of the glazing (position 1) will occur, if the surface temperature of the glass is significantly lower than the outside air temperature and the dew point (the temperature at which the vapor content in the air becomes wet) air is higher than the temperature of the glass pane. The surface temperature of the exterior pane is a function of the following factors:

  • The flow of heat that penetrates the windows from the inside to the outside, which depends on the temperature difference and also on the U-value of the glass panes,
  • The exchange of heat in convection to the outside air,
  • Heat losses from radiation

 

Condensation in positions 2 and 3

The appearance of hoar-frost inside the inner sides of a double glazing indicates that the air gap or the gas content is no longer watertight. The hygroscopic molecules, that are used, reach saturation very quickly. Also, the outside humid air enters the perimeter sealing and as a result it forms condensate points in the double glazing positions 2 and 3 and therefore the glazing must be replaced because the process is irreversible.

 

Condensation in Position 4

Condensation in Position 4 depends on:

  • The indoor temperature
  • The outside temperature
  • Moisture formed inside the chambers of the double/triple glazing
  • Ventilation
  • Surface temperature of the wall

Of course, the additional improvement of the heat system is ensured by Swisspacer bars. This material has the ability to increase the surface temperature of the inner glass by reducing the risk of moisture.

What is the best way of welding a double glazing unit?

The best way to weld a double glazing is determined by the following factors:

  1. good quality and condition of silicates
  2. 1st sealing with butyl sealant
  3. 2nd sealing with cool sealant (thiocol)
  4. amount of sealant

At this point, it is important to note that when we say “butyl sealant” we do not mean the double-sided strip, which is used only as an auxiliary element in the welding process. In case that, instead of butyl, a double-sided tape is used, then it is certain that the double unit becomes weak to cope with the moisture effect that will occur inside the glazing. As far as cool sealant (thiocol) is concerned, it is worth mentioning that it consists of two materials and does not change by temperature fluctuations. Once it is placed in the double / triple glazing unit and polymerized, then it will not change again. For this reason, cool sealant (thiocol) is almost entirely preferred in double/triple glazing welding. On the contrary to the hot sealant, which is significantly affected by weather changes.

What is SWISSPACER?

Traditionally, the spacers of the double glazing units were made of aluminum, which is extremely conductive to the heating and allows it to pass through the windows. Now, SWISSPACER gives the solution needed, ensuring less energy consumption and maintaining a comfortable internal temperature.

 

Material Thermal conductivity (W/mK)
Aluminum 160
Stainless steel 15-17
Swisspacer 0.16

 

file_pdf_download-128
PDF

What is the "lifespan" of a double glazing unit?

The lifetime of a sealed unit depends on the quality and the quantity of sealing and desiccant materials used, and also on how well the unit has been sealed. It is also necessary to emphasize that the life of a double / triple unit also depends significantly on the run-off holes. The frame, in which the insulated glazing is to be installed, must have holes through which the water will escape, because if it does not have these holes, then the water is trapped in the frame, creates moisture and consequently also affects negatively the glazing.

Under which criteria should I choose an energy double glazing?

The choice of the type of double glazing must be based on:

  • The climate (a different kind of glass will be placed at a house in Florina from a house in Crete)
  • The needs of the house / working place and also the consumer’s needs
  • Whether or not there are sunshades (awning, shutters, etc.).

What is the role of Laminated at the double glazing units?

The types of laminated glass used in a double glazing unit are:

  • Laminated glass with plain film
  • Laminated glass with acoustic film

And it can be used as follows:

  • Laminated glass – spacer (?) + argon/air – common glass
  • Laminated glass – spacer (?) + argon/air – Laminated glass

The benefits of laminated glass in a double unit are:

  1. Provide safety against accidents and injuries. The laminated glass pane consists of two or more glass panes, which are bonded together with a special adhesive film. They are essentially a body, which provides more safety and durability than a common glass. Thus, when a laminated glass breaks, the pieces that will be formed remain attached to the interposed film, which means that the glazing does not collapse to be considered dangerous.
  2. Enhancement of sound insulation (in both cases but more with the acoustic film)
  3. Reduction of UV radiation

What is the difference between the soft coating and the hard coating at energy glass panes?

Energy glass panes are used only in the construction of a double / triple glazing unit and in fact they are glass panes, on the surface of which there is a special coating of metallic oxides. This coating has high reflectance in the infrared solar radiation, or in other words to heat. However, this coating allows the light to pass through the double unit, regardless of the thermal insulation it provides. Energy glass panes are distinguished in hard coating and soft coating. The hard coating is achieved by the chemical spraying method, or by the pyrolytic method, which takes place during the glass production process (on line). Nevertheless, the perpetual development of technology creates both new needs and new products. Such a product in the glass industry is the Soft-coated Energy Glass Panes, which is achieved by natural spraying. Physical spraying is performed by an off line technique, which is independent of the production process of the glass. Essentially, the created coating consists of films with multiple metal oxides. Clearly between both, the soft coating has better results, and despite this the hard coating is now outdated.

Apart from energy glass panes, what other elements should the double glazing unit have to provide an efficient energy performance (on thermal insulation)?

In order to ensure an efficient energy performance in a double glazing, apart from the glass panes, the spacer also plays a key role. Specifically:

1.The material of the spacer

The usual double / triple glazing units are made of aluminum. However, the materials that maximize the performance of the double unit are the stainless steel and the plastic/swisspacer. SWISSPACER is considered to be a unique material of its kind, an airtight barrier, which maximizes energy efficiency and reduces energy consumption bills. This material not only improves the double glazing units’ performance but also prevents condensation, appearance of moisture and mold on the glass panes.

2.The size of the spacer

It is important to emphasize that the most suitable size for the spacer of a double unit is 16mm. This factor achieves the best coefficients for the energy performance of the double/triple unit. From this size and beyond, increasing the size of the spacer does not improve its performance, either it will remain stable or it will decrease.

 

file_pdf_download-128

DECLARATION OF PERFOMANCE

the smaller the U-value the more efficient the double glazing

What is a triple glazing and why should I use it?

The triple glazing unit consists of three glass panes and two chambers. It can be used as an insulated glass pane because it greatly enhances the energy performance of the triple unit. For example,

 

file_pdf_download-128

DECLARATION OF PERFOMANCE

 

dB double glazing < dB triple glazing   

(the higher the dB value, the greater the sound insulation of glazing – in this case the installation of a Laminated glass with soundproofing film would further enhance the sound insulation)

Ug-value double glazing > Ug-value triple glazing   

(the smaller Ug-value the more efficient the glazing)

Solar energy transmission: In winter we need heat in our space, while in summer we prefer the opposite. Therefore, the coefficient should be as small as possible.

Solar energy transmission with double glazing  > Solar energy transmission with triple glazing

Solar energy reflection: this coefficient should be as large as possible.

Solar energy reflection with double glazing < Solar energy reflection with triple glazing 

Therefore, triple glazing significantly surpasses the double glazing.

Solar  Factor with double glazing > Solar Factor with triple glazing

(The lower the price the less solar energy transfered into the interior).

From what factors depends the depreciation in money I will have from replacing my windows?

Quenching money for replacing frames entails energy savings and depends on many factors. Some of them are:

• The amount of energy used for heating or cooling consumption
• The price of oil and electricity
• The square meters of the building and the glass panes to be placed
• The type of energy glass pane
• The kind of welding and the materials to be used for bending the glass pane etc
• The type of spacer (spacer)

Is it enough to replace the old windows of my house with "Energy windows" to ensure substantial energy savings?

First of all, it is vital to know that each building is the composition of many elements, such as the roof, the frames, the walls, the floor. The heat of a building escapes from everywhere. For this reason, the replacement of glass panes is necessary because:

  1. Replacement of glass panes is simple and quick
  2. From the frames of a building, it escapes up to 30% (approximately) of its heat
  3. This replacement has a relatively low cost and is more advantageous than other interventions
  4. The results are immediate and the benefits visible

All types of double glazing are also energy windows?

Absolutely not. Thermal insulation performance of energy glazing is not comparable to conventional double-glazing. In other words, energy savings are only achieved with energy double and triple glazing. For example, the difference between an energy glazing and a common double glazing is as huge as the difference between a common double with a single glazing. It is also necessary to make it clear that all energy glass panes are not identical to each other, so they do not all have the same technical specifications and characteristics.

Why should I put energy glasses in my house?

If we analyze the responsibilities of the structural elements in the heat dissipation in an average house we realize that:

• 20% of heat loss is due to the roof
• 25% of the thermal loss is due to the walls
• 20% of the heat loss is due to the floor
• 35% of heat loss is due to windows

Summing up all the above, we can easily conclude that the easiest, the most economical, the most ecological but also the most efficient way to reduce heat loss and consequently save money is achieved by installing energy glass panes.

Energy glass:

• Reflects the infrared sunlight (heat)
• Acts as a shield against indirect heat from the surrounding area
• Has more efficient thermal insulation in the winter
• It is easier to cool in the summer
• Significantly reduces annual heating and cooling costs
• Contributes substantially to the protection of the environment
• Reduces up to 70% incoming ultraviolet radiation (depending on the type of glass pane)
• It has a minimal cost difference from common double glazing

What does “Four Seasons Energy Glass” mean?

The classification of energy glasses in “Two Seasons” and “Four Seasons” is a misconception that divides. In fact, the energy glass has technical specifications that characterize it and compare it to other types of glasses, so that it can finally be decided, if it is more appropriate than another. In analyzing the technical specifications of an energy glazing we consider factors such as U-value value, light transmission and light reflection, solar energy transmission and solar energy reflection and solar factor. For example, an energy glazing can have a good coefficient of light transmission, while another has a better coefficient of energy transmission than the first one. The consumer in the process of selecting energy glazing must assess the type of glass he will eventually place based on his geographical area and assess the needs of his home / working place. In conclusion, it is these factors that characterize each energy glass separately and not its classification as “Two or Four Seasons Glass”.

How is the Declaration of Performance and what do its coefficients and values express?

DECLARATION OF PERFOMANCE

Energy glass (Low-e) 6mm / 16mm Argon 90% / Clear 5mm
ESSENTIAL CHARACTERISTICS HARMONISED TECHNICAL SPECIFICATION MEASUREMENT PERFORMANCE
Safety in the case of fire
Resistance to fire EN 13501-2 NPD
Reaction to fire EN 13501-1 NPD
External fire performance EN 13501-5 NPD
Safety in use
Bullet resistance EN 1063 NPD
Explosion resistance EN 13541 NPD
Burglar resistance EN 356 NPD
Pendulum body impact resistance EN 12600 NPD
Resistance against sudden temperature changes and temperature differentials EN 572 [ ° Κ] NPD
Wind, snow, permanent and imposed load resistance EN 13474 mm NPD
Protection against noise
Direct airborne sound reduction (dB) EN 12758 dB NPD
Thermal properties
Declared emissivity U-value (W/m²K) EN 673 W/m²K

1

Radiation properties
Light transmission EN 410 %

64

Light reflection EN 410 %

25

Solar energy characteristics
Solar transmission EN 410 %

37

Solar reflection EN 410 %

32

Solar factor EN 410 %

39

*NPD = No Performance Determined

U value is a measure of the insulation capacity. In other words, the ability of a material to act as a thermal “barrier” between indoor and outdoor air.

Ug = coefficient of thermal conductivity of a double glazing unit 

Uf = coefficient of thermal conductivity of a window frame

Uw = coefficient of thermal conductivity of a window system

Actually, Ug indicates the sum of the energy we need to consume in order to maintain a temperature difference between the spaces separating the materials. The lower this value is, the more efficient the glazing is and so, the less watt has to be consumed.

LightTransmission and Light Reflection: these factors are directly related to the climate in which the double glazing unit will be installed. Moreover, they depend on the needs and requirements of the building.

Energy Transmission and Energy Reflection: these factors are also directly related to the climate in which the double glazing unit will be installed. Moreover, they depend on the needs and requirements of the building.

Solar Factor: is the percentage of solar energy passing through a space from the double glazing. The lower this value is, the less solar energy passes inside the space.

What can I do to improve the thermal insulation of my glass panes?

There are 3 ways to improve the glazing of your house/working place etc.

  • Use energy double or triple glazing
  • Increase as much as possible the space of the glass up to 16mm.
  • Use noble gas such as argon instead of normal air in the gap space of the glass pane.
  • Place swisspacer or stainless steel spacer
  • Apply: 1st step with butyl sealant and 2nd step with cool sealant (thiocol)

 


 

DECLARATION OF PERFORMANCE

Energy glass (Low-e) 6mm /12mm Argon 90%/ Clear 5mm
Energy glass (Low-e) 6mm / 16mm Argon 90% / Clear 5mm
ESSENTIAL CHARACTERISTICS MEASUREMENT PERFORMANCE MEASUREMENT PERFORMANCE
Thermal properties
Declared emissivity U-value (W/m²K) W/m²K

1.2

W/m²K

1

Radiation properties
Light transmission % 64 % 64
Light reflection % 25 % 25
Solar energy characteristics
Solar transmission % 37 % 37
Solar reflection % 32 % 32
Solar factor % 40 % 39

 

The appropriate size of the spacer is 16mm. Below this size, the double glazing performance is quite low.

(the smaller the Ug-value the more efficient the double glazing) 

 

 


DECLARATION OF PERFORMANCE

Energy glass (Low-e) 6mm /16mm Argon 90%/ Clear 5mm
Energy glass (Low-e) 6mm /20mm Argon 90%/ Clear 5mm
ESSENTIAL CHARACTERISTICS MEASUREMENT PERFORMANCE MEASUREMENT PERFORMANCE
Thermal properties
Declared emissivity U-value (W/m²K) W/m²K

1

W/m²K

1.1

Radiation properties
Light transmission % 64 % 64
Light reflection % 25 % 25
Solar energy characteristics
Solar transmission % 37 % 37
Solar reflection % 32 % 32
Solar factor % 39 % 39

 

The appropriate size of the spacer is 16mm. If this size increases, the double glazing performance will either remain constant or decreased.    

(the smaller Ug-value the more efficient the double glazing)

 


 

 

DECLARATION OF PERFOMANCE

Energy glass (Low-e) 6mm /16mm Argon 90%/ Clear 5mm
Energy glass (Low-e) 6mm /16mm Air 100% / Clear 5mm
ESSENTIAL CHARACTERISTICS HARMONISED TECHNICAL SPECIFICATION MEASUREMENT PERFORMANCE HARMONISED TECHNICAL SPECIFICATION MEASUREMENT PERFORMANCE
Thermal properties
Declared emissivity U-value (W/m²K) EN 673 W/m²K

1

EN 673 W/m²K

1.3

Radiation properties
Light transmission EN 410 % 64 EN 410 % 64
Light reflection EN 410 % 25 EN 410 % 25
Solar energy characteristics
Solar transmission EN 410 % 37 EN 410 % 37
Solar reflection EN 410 % 32 EN 410 % 32
Solar factor EN 410 % 39 EN 410 % 40


Argon instead of Air, in the double glazing unit, improves U-value and therefore it significantly enhances its performance.

(the smaller the U-value the more efficient the double glazing)

 


 

DECLARATION OF PERFORMANCE

Energy glass (Low-e) 6mm /16mm Argon 90%/ Clear 5mm
Clear 6mm /16mm Argon 90%/ Clear 5mm
ESSENTIAL CHARACTERISTICS MEASUREMENT PERFORMANCE MEASUREMENT PERFORMANCE
Thermal properties
Declared emissivity U-value (W/m²K) W/m²K

1

W/m²K

2.6

Radiation properties
Light transmission % 64 % 64
Light reflection % 25 % 25
Solar energy characteristics
Solar transmission % 37 % 37
Solar reflection % 32 % 32
Solar factor % 39 % 39

Ug variance = 1,6
(the smaller Ug-value the more efficient the glazing)

LightTransmission and Light Reflection: these factors are directly related to the climate in which the double glazing unit will be installed. Moreover, they depend on the needs and requirements of the building.

Solar energy transmission: In winter we need heat in our space, while in summer we prefer the opposite. Therefore the coefficient should be as small as possible.

Solar energy reflection: this coefficient should be as large as possible.

Therefore, double glazing with energy glass panes (low-e) significantly surpasses double glazing with common glass panes .

Solar  Factor variance = 39
Solar Factor: is the percentage of solar energy passing through a space from the  glazing. The lower this value is, the less solar energy passes inside the space.
(The lower the price the less solar energy transfered into the interior).

Why do glass panes get moisture?

First of all, it is important to clarify that the moisture inside the double glazing unit is an extremely different phenomenon than the moisture appeared on the frames’ surfaces and thus the glazing. Thermal losses in a frame depend on four factors:

A. the material of the frame

B. the type of the glass panes

C. the percentage of frame’s coverage in the frame and

D. the length of the thermal bridge formed at the point where the glazing joins the frame

 

More specifically, regarding the glass, the phenomenon of moisture on glazing and generally in window frames occurs in four cases.

Assuming that we have a window with a  double glazing unit, for example 4mm – 16mm – 4mm

  • In position 1 or outside position of the first pane to the outside environment,
  • In position 2 or inner position of the first pane inside the gap,
  • In position 3 or outside of the second pane inside the gap,
  • In position 4 or the inner side of the second pane to the inside environment of the space.

 

Condensation in the inner position (position 4) usually starts from the corners, as a result of the strong cooling, created by the existence of the thermal bridge. The surface moisture on the outside position of the glass (position 1) rarely starts at the corners, once the edges of the outside glass pane are usually warmed and the coolest point on the outside of the pane is usually located in its central region.
However, it is necessary to note that over time the persistent condensation becomes a fertile place for the growth of mold and bacteria. Mold can get into the air we breathe, aggravate breathing conditions or cause other health problems.

Why the spacer in the double glazing unit is so important?

pacers are responsible for the distance between the panes of a window. However, the quality of the spacers depends on the conductivity “λ” or otherwise the thermal conductivity of the material from which they are made. The conductivity “λ” of a material indicates the thermal power or heat – expressed in watt (W) – which penetrates a layer of 1m thickness material over 1h if the material surface is 1m² and there is a temperature difference between the original of the final side 1 Kelvin (= 1 ° C).

Conductivity is important because it shows us if the material has thermal insulation capabilities or not and how much. At this point, let us clarify that the lower the value, the better the material used on the frame. To make this easier to understand, the following table shows the conductivity factors for various materials.

Material Thermal conductivity (W/mK)
Aluminum 160
Stainless steel 15-17
Swisspacer 0.16

What forms of humidity we can encounter in a double glazing unit?

Condensation in Position 1

The moisture effect on the exterior surface of the glazing (position 1) will occur, if the surface temperature of the glass is significantly lower than the outside air temperature and the dew point (the temperature at which the vapor content in the air becomes wet) air is higher than the temperature of the glass pane. The surface temperature of the exterior pane is a function of the following factors:

  • The flow of heat that penetrates the windows from the inside to the outside, which depends on the temperature difference and also on the U-value of the glass panes,
  • The exchange of heat in convection to the outside air,
  • Heat losses from radiation

 

Condensation in positions 2 and 3

The appearance of hoar-frost inside the inner sides of a double glazing indicates that the air gap or the gas content is no longer watertight. The hygroscopic molecules, that are used, reach saturation very quickly. Also, the outside humid air enters the perimeter sealing and as a result it forms condensate points in the double glazing positions 2 and 3 and therefore the glazing must be replaced because the process is irreversible.

 

Condensation in Position 4

Condensation in Position 4 depends on:

  • The indoor temperature
  • The outside temperature
  • Moisture formed inside the chambers of the double/triple glazing
  • Ventilation
  • Surface temperature of the wall

Of course, the additional improvement of the heat system is ensured by Swisspacer bars. This material has the ability to increase the surface temperature of the inner glass by reducing the risk of moisture.

What is the best way of welding a double glazing unit?

The best way to weld a double glazing is determined by the following factors:

  1. good quality and condition of silicates
  2. 1st sealing with butyl sealant
  3. 2nd sealing with cool sealant (thiocol)
  4. amount of sealant

At this point, it is important to note that when we say “butyl sealant” we do not mean the double-sided strip, which is used only as an auxiliary element in the welding process. In case that, instead of butyl, a double-sided tape is used, then it is certain that the double unit becomes weak to cope with the moisture effect that will occur inside the glazing. As far as cool sealant (thiocol) is concerned, it is worth mentioning that it consists of two materials and does not change by temperature fluctuations. Once it is placed in the double / triple glazing unit and polymerized, then it will not change again. For this reason, cool sealant (thiocol) is almost entirely preferred in double/triple glazing welding. On the contrary to the hot sealant, which is significantly affected by weather changes.

What is SWISSPACER?

Traditionally, the spacers of the double glazing units were made of aluminum, which is extremely conductive to the heating and allows it to pass through the windows. Now, SWISSPACER gives the solution needed, ensuring less energy consumption and maintaining a comfortable internal temperature.

 

Material Thermal conductivity (W/mK)
Aluminum 160
Stainless steel 15-17
Swisspacer 0.16

 

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What is the "lifespan" of a double glazing unit?

The lifetime of a sealed unit depends on the quality and the quantity of sealing and desiccant materials used, and also on how well the unit has been sealed. It is also necessary to emphasize that the life of a double / triple unit also depends significantly on the run-off holes. The frame, in which the insulated glazing is to be installed, must have holes through which the water will escape, because if it does not have these holes, then the water is trapped in the frame, creates moisture and consequently also affects negatively the glazing.

Under which criteria should I choose an energy double glazing?

The choice of the type of double glazing must be based on:

  • The climate (a different kind of glass will be placed at a house in Florina from a house in Crete)
  • The needs of the house / working place and also the consumer’s needs
  • Whether or not there are sunshades (awning, shutters, etc.).

What is the role of Laminated at the double glazing units?

The types of laminated glass used in a double glazing unit are:

  • Laminated glass with plain film
  • Laminated glass with acoustic film

And it can be used as follows:

  • Laminated glass – spacer (?) + argon/air – common glass
  • Laminated glass – spacer (?) + argon/air – Laminated glass

The benefits of laminated glass in a double unit are:

  1. Provide safety against accidents and injuries. The laminated glass pane consists of two or more glass panes, which are bonded together with a special adhesive film. They are essentially a body, which provides more safety and durability than a common glass. Thus, when a laminated glass breaks, the pieces that will be formed remain attached to the interposed film, which means that the glazing does not collapse to be considered dangerous.
  2. Enhancement of sound insulation (in both cases but more with the acoustic film)
  3. Reduction of UV radiation

What is the difference between the soft coating and the hard coating at energy glass panes?

Energy glass panes are used only in the construction of a double / triple glazing unit and in fact they are glass panes, on the surface of which there is a special coating of metallic oxides. This coating has high reflectance in the infrared solar radiation, or in other words to heat. However, this coating allows the light to pass through the double unit, regardless of the thermal insulation it provides. Energy glass panes are distinguished in hard coating and soft coating. The hard coating is achieved by the chemical spraying method, or by the pyrolytic method, which takes place during the glass production process (on line). Nevertheless, the perpetual development of technology creates both new needs and new products. Such a product in the glass industry is the Soft-coated Energy Glass Panes, which is achieved by natural spraying. Physical spraying is performed by an off line technique, which is independent of the production process of the glass. Essentially, the created coating consists of films with multiple metal oxides. Clearly between both, the soft coating has better results, and despite this the hard coating is now outdated.

Apart from energy glass panes, what other elements should the double glazing unit have to provide an efficient energy performance (on thermal insulation)?

In order to ensure an efficient energy performance in a double glazing, apart from the glass panes, the spacer also plays a key role. Specifically:

1.The material of the spacer

The usual double / triple glazing units are made of aluminum. However, the materials that maximize the performance of the double unit are the stainless steel and the plastic/swisspacer. SWISSPACER is considered to be a unique material of its kind, an airtight barrier, which maximizes energy efficiency and reduces energy consumption bills. This material not only improves the double glazing units’ performance but also prevents condensation, appearance of moisture and mold on the glass panes.

2.The size of the spacer

It is important to emphasize that the most suitable size for the spacer of a double unit is 16mm. This factor achieves the best coefficients for the energy performance of the double/triple unit. From this size and beyond, increasing the size of the spacer does not improve its performance, either it will remain stable or it will decrease.

DECLARATION OF PERFORMANCE

Energy glass (Low-e) 6mm /16mm Argon 90%/ Clear 5mm
Energy glass (Low-e) 6mm /20mm Argon 90%/ Clear 5mm
ESSENTIAL CHARACTERISTICS MEASUREMENT PERFORMANCE MEASUREMENT PERFORMANCE
Thermal properties
Declared emissivity U-value (W/m²K) W/m²K

1

W/m²K

1.1

Radiation properties
Light transmission % 64 % 64
Light reflection % 25 % 25
Solar energy characteristics
Solar transmission % 37 % 37
Solar reflection % 32 % 32
Solar factor % 39 % 39

 

the smaller the U-value the more efficient the double glazing

What is a triple glazing and why should I use it?

The triple glazing unit consists of three glass panes and two chambers. It can be used as an insulated glass pane because it greatly enhances the energy performance of the triple unit. For example,

 

 

    Double glazing unit Triple glazing unit
Energy glass (Low-e) 6mm /16mm Argon 90%/ Clear 5mm
Energy glass (Low-e) 6mm /16mm Argon 90%/ Clear 4mm /16mm Argon 90%/ Laminated 33.1
ESSENTIAL CHARACTERISTICS HARMONISED TECHNICAL SPECIFICATION MEASUREMENT PERFORMANCE HARMONISED TECHNICAL SPECIFICATION MEASUREMENT PERFORMANCE
Protection against noise
Direct airborne sound reduction (dB) EN 12758

34 (-1 ; -3)

EN 12758

37 (-2 ; -8)

Thermal properties
Declared emissivity U-value (W/m²K) EN 673 W/m²K

1

EN 673 W/m²K

0.8

Radiation properties
Light transmission EN 410 % 64 EN 410 % 59
Light reflection EN 410 % 25 EN 410 % 28
Solar energy characteristics
Solar transmission EN 410 %

37

EN 410 %

32

Solar reflection EN 410 %

32

EN 410 %

33

Solar factor EN 410 %

39

EN 410 %

37

dB double glazing < dB triple glazing   

(the higher the dB value, the greater the sound insulation of glazing – in this case the installation of a Laminated glass with soundproofing film would further enhance the sound insulation)

Ug-value double glazing > Ug-value triple glazing   

(the smaller Ug-value the more efficient the glazing)

Solar energy transmission: In winter we need heat in our space, while in summer we prefer the opposite. Therefore, the coefficient should be as small as possible.

Solar energy transmission with double glazing  > Solar energy transmission with triple glazing

Solar energy reflection: this coefficient should be as large as possible.

Solar energy reflection with double glazing < Solar energy reflection with triple glazing 

Therefore, triple glazing significantly surpasses the double glazing.

Solar  Factor with double glazing > Solar Factor with triple glazing

(The lower the price the less solar energy transfered into the interior).