planning:thermal_protection:windows:types_of_glazing_and_their_specific_values
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planning:thermal_protection:windows:types_of_glazing_and_their_specific_values [2015/05/09 15:04] – [Insulating glass: intermediate stage in need of improvement] wolfgangfeist@googlemail.com | planning:thermal_protection:windows:types_of_glazing_and_their_specific_values [2022/04/19 10:53] – [Triple glazing with two low-e layers: optimum quality for innovative construction and modernisation] wfeist | ||
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At the beginning of the 1970s, most windows in Germany had single glazing: {{ : | At the beginning of the 1970s, most windows in Germany had single glazing: {{ : | ||
* the U-value was about **5.5 W/(m²K)**, | * the U-value was about **5.5 W/(m²K)**, | ||
+ | |||
* the annual heat losses through 1 m² of such a window were equivalent to the energy expenditure from 60 litres of heating oil | * the annual heat losses through 1 m² of such a window were equivalent to the energy expenditure from 60 litres of heating oil | ||
+ | |||
=> Assuming average energy prices in Germany, each square metre of such a window " | => Assuming average energy prices in Germany, each square metre of such a window " | ||
- | Not only the energy losses are increased, however. | + | Not only the energy losses are increased, however. |
\\ | \\ | ||
==== " | ==== " | ||
The so-called insulating glass panes were somewhat better. They were installed in new and {{ : | The so-called insulating glass panes were somewhat better. They were installed in new and {{ : | ||
- | * The thermal transmittance coefficient is reduced by the air layer to about **2.8 W/(m²K)**, which means that the heat losses are about half of those of the single glazing. | + | * The thermal transmittance coefficient is reduced by the air layer to about **2.8 W/(m²K)**, which means that the heat losses are about half of those of the single glazing. |
- | * The interior surface temperatures of double glazing on very cold days are about 7.5 °C. There are no frost patterns any more, but the window surface is still unpleasantly cold. In cold weather, there will be condensation, | + | |
+ | * The interior surface temperatures of double glazing on very cold days are about 7.5 °C. There are no frost patterns any more, but the window surface is still unpleasantly cold. In cold weather, there will be condensation, | ||
* The heat losses cost about € 21 per m² each year - and that adds up in 15 years to more than the initial cost of the window itself. Many windows in existing buildings still have these so called " | * The heat losses cost about € 21 per m² each year - and that adds up in 15 years to more than the initial cost of the window itself. Many windows in existing buildings still have these so called " | ||
\\ | \\ | ||
==== Double low-e glazing: | ==== Double low-e glazing: | ||
- | Significant progress | + | Significant progress |
- | * Furthermore, | + | * Furthermore, |
* An interesting fact is that " | * An interesting fact is that " | ||
- | | + | |
- | * The average interior surface temperature is about 13°C even at frosty outdoor temperatures. However, there is still cold air descent ocurring at the window and uncomfortable temperature stratification may still occur in the room. In Central Europe condensation only occurs on the inside on the edges with this quality of glazing .\\ | + | |
+ | |||
+ | * The average interior surface temperature is now some 13°C in minimum | ||
\\ | \\ | ||
- | ==== Triple glazing with two low-e layers: | + | ==== Triple glazing with two low-e layers: |
The breakthrough for energy efficient construction in Germany was triple glazing using two low-e-layers. | The breakthrough for energy efficient construction in Germany was triple glazing using two low-e-layers. | ||
+ | |||
* It consists of two spaces between panes with one low-e coating each and inert gas filling, resulting in **U-values between 0.5 and 0.8 W/(m²K)**. | * It consists of two spaces between panes with one low-e coating each and inert gas filling, resulting in **U-values between 0.5 and 0.8 W/(m²K)**. | ||
+ | |||
* In order to achieve this level of quality for the whole window and not just for the glazing ** a well-insulated window frame and a thermally separated spacer ** should also be used in addition. | * In order to achieve this level of quality for the whole window and not just for the glazing ** a well-insulated window frame and a thermally separated spacer ** should also be used in addition. | ||
- | => The result is a " | + | => The result is a " |
- | If one also considers | + | If one also takes into account |
\\ | \\ | ||
- | The windows' | + | The windows' |
\\ | \\ | ||
The Passive House window excels in that it not only has lower heat losses, but also provides improved comfort. ** Even with cold outdoor temperatures like -15°C, the interior surface temperature does not fall below 17°C.** | The Passive House window excels in that it not only has lower heat losses, but also provides improved comfort. ** Even with cold outdoor temperatures like -15°C, the interior surface temperature does not fall below 17°C.** | ||
* Thus, there is no perceptible "cold radiation" | * Thus, there is no perceptible "cold radiation" | ||
- | | + | |
+ | | ||
In these circumstances the thermal comfort in the room is ensured independently of the type of heating supply. That this was made possible, is due in considerable part to the the improved windows.\\ | In these circumstances the thermal comfort in the room is ensured independently of the type of heating supply. That this was made possible, is due in considerable part to the the improved windows.\\ | ||
\\ | \\ | ||
- | **Here are the important components of the thermal | + | **Here are the important components of a window |
* Triple glazing with two low-e coatings, | * Triple glazing with two low-e coatings, | ||
+ | |||
* Insulating window frames, | * Insulating window frames, | ||
+ | |||
* Insulating mullion-transom constructions, | * Insulating mullion-transom constructions, | ||
+ | |||
* Thermally separated spacers, | * Thermally separated spacers, | ||
+ | |||
* Tools for the thermal-bridge-free assembly and airtight installation of windows.\\ | * Tools for the thermal-bridge-free assembly and airtight installation of windows.\\ | ||
\\ | \\ | ||
|{{ : | |{{ : | ||
- | |// | + | |// |
\\ | \\ | ||
===== Conclusion ===== | ===== Conclusion ===== | ||
- | Passive House windows are high quality products which are now produced and supplied by __**more than 50 manufacturers**__. The energy savings achieved by these windows do not amount to just a few percent, in fact they amount to more than half of the heat lost through windows. | + | Passive House windows are high quality products which are now produced and supplied by __**more than 200 manufacturers**__. The energy savings achieved by these windows do not amount to just a few percent, in fact they amount to more than half of the heat lost through windows. |
\\ | \\ | ||
- | |{{ :picopen:glasing_passive_house.png }}| | + | |{{ :picopen:glasing_passive_house22..png }}| |
|//**The development of constantly improved glazing:\\ | |//**The development of constantly improved glazing:\\ | ||
from single-galzing (on the far left) to the Passive-House-suitable\\ | from single-galzing (on the far left) to the Passive-House-suitable\\ |
planning/thermal_protection/windows/types_of_glazing_and_their_specific_values.txt · Last modified: 2022/05/02 19:40 by wfeist