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# 175245 22-Jun-2015 21:16
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Retrofitting double glazing both end of our hall in old villa. Low E glass from memory (no argon)

They have replaced 3 of the four glass panes around the front door with double glazing glass while the 4th window is still single as it is inside the door which is being replaced.

Outside its a chilly 0.8C but there is no discernible difference in temperature when I touch the glass of the double glazing units vrs the original 50+ year units.

(frames all wood).

I'm a bit confused about this as I thought the DG glass panes would be less cold to touch ?

Is it just because it so cold outside and glass is such a good conducter that it sucking enough heat that it feels cold either way?


A.

Have one of those IR thermometer guns on back order anyway so might measure the actual temperature of the glass panes to put numbers to the impression...



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  # 1329556 22-Jun-2015 21:33
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Not sure about the technical aspect but I would imagine that retrofitted units would be less efficient than modern units designed to function as DG with thermal breaks etc.

What would confuse me more is why the inside pane has not been heated as a result of the heating indoors. If the house is warmer than the outside air then everything in the house should be at an ambient temperature greater than that outside.





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  # 1329575 22-Jun-2015 22:15
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Glass is a good conductor of heat, so your hand will feel cold when touching the inner pane because the glass is conducting heat away from your hand.
The wooden frames will feel warmer because wood is a poor conductor of heat.

The double glazed units will be reducing the amount of heat escaping to the outside.

 
 
 
 


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  # 1329585 22-Jun-2015 22:19
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You say you are retro fitting them, are they proper IGUs , to the same thickness? 

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  # 1329586 22-Jun-2015 22:22
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The IR thermometer will probably "see" through the glass and measure the outside temperature.  Or it will pick up reflections in the glass.  You'd need a probe like an NTC or thermocouple to measure the glass surface temperature.

The R value of double glazing is still only about 0.3.  You might not feel much difference, but over a large surface the small difference adds up.  I don't think your hands will accurately feel the difference of cold temperature.




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  # 1329598 22-Jun-2015 22:52
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Niel: The IR thermometer will probably "see" through the glass and measure the outside temperature.  Or it will pick up reflections in the glass.  You'd need a probe like an NTC or thermocouple to measure the glass surface temperature.

The R value of double glazing is still only about 0.3.  You might not feel much difference, but over a large surface the small difference adds up.  I don't think your hands will accurately feel the difference of cold temperature.


if anything IR will be reflected by glass



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  # 1329689 23-Jun-2015 08:50
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mattwnz: You say you are retro fitting them, are they proper IGUs , to the same thickness? 



I'm not doing it, getting some blokes in. :-)

They have pulled out the original wood frames out of the wall replaced the glass and put them back into the wall, wood surrounds everything. Windows don't open at all as they are the glass surrounds arround front door.

Just puzzled why the _glass_ is the same temperature.

A.



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  # 1329695 23-Jun-2015 08:56
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Niel: The IR thermometer will probably "see" through the glass and measure the outside temperature.  Or it will pick up reflections in the glass.  You'd need a probe like an NTC or thermocouple to measure the glass surface temperature.

The R value of double glazing is still only about 0.3.  You might not feel much difference, but over a large surface the small difference adds up.  I don't think your hands will accurately feel the difference of cold temperature.


This is what I'm hoping.
Ie once all glass is done, the inside warms enough that it's noticeably warmer to touch. Certainly the double glazing units at work are warm but they heat inside too.

're IR thermometer.Don't have access to thermocouple at home as the ones at work attached to great big machines.Could I tape something opaque to the window and measure the temperature of that instead. ? Masking tape.

A.


 
 
 
 




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  # 1329704 23-Jun-2015 09:11
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Measuring glass temperature of double glazing units.

http://gaia.lbl.gov/btech/papers/38117.pdf

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  # 1329713 23-Jun-2015 09:16
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I wouldn't worry too much about the surface temperature, the idea is it reduces the heat loss. Sure it may still feel cold, but not as cold, and less heat should escape.

mdf

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  # 1329714 23-Jun-2015 09:17
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afe66:
mattwnz: You say you are retro fitting them, are they proper IGUs , to the same thickness? 



I'm not doing it, getting some blokes in. :-)

They have pulled out the original wood frames out of the wall replaced the glass and put them back into the wall, wood surrounds everything. Windows don't open at all as they are the glass surrounds arround front door.

Just puzzled why the _glass_ is the same temperature.

A.


Glass is a good conducter of heat, so any time anything warmer touches it (e.g. your hand) it will conduct away heat and therefore feel cold. Wood is a poor conducter, so doesn't have the same effect. Touch a glass table top inside your house (or anything else that's a good conductor like metal) and it will also feel cold even though it is obviously room temperature. 

Double glazing essentially acts like a thermal break _between_ the panes of glass. The inside pane of glass should be room temperature (ish - there's obviously still some heat loss), the outside pane the outside temperature. The individual panes of glass will still conduct heat, but they won't conduct heat between the panes.

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  # 1329735 23-Jun-2015 09:48
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Heat transfer(and sound) through double glazing is determined by the type of glass, and how far apart they are (internal spacer)

At work we have a chest freezer that has had the lid removed and two sample frames installed. One is double glazed, one is single glazed. There is a definit temperature difference when placing hands on it (designed as sample for home shows)

So they should be different temperatures, but as someone has pointed out, it's a bit misleading when using hands.

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  # 1329803 23-Jun-2015 10:46
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k1w1k1d: Glass is a good conductor of heat, so your hand will feel cold when touching the inner pane because the glass is conducting heat away from your hand.
The wooden frames will feel warmer because wood is a poor conductor of heat.

The double glazed units will be reducing the amount of heat escaping to the outside.


Actually glass is a very poor conductor of heat if it was a good conductor glass blowers making ornamental glass objects would never be able to hold onto it with their fingers whilst heating it

DG glass is no different than ordinary glass it's the gap between the two panes that stops heat from escaping (but only if a vacuum is formed between the two panes) if the gap still contains air then it's only going to be slightly better than a single pane   

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  # 1329815 23-Jun-2015 11:07
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The R value of double glazing is still only about 0.3.
Of a typical low quality aluminium double glazed window, yes, but with argon and low-e on wood it should be able to do double that.

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  # 1329819 23-Jun-2015 11:12
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to be honest, i am not sure if double glazing actually does much to retain heat when the rest of the house is leaking heat. yes, if the walls, floor, joinery, roof are all well insulated then going from single to double glaze will make a world of difference, like putting a cap on a bottle. not sure ... i guess you will tell us next year?




Swype on iOS is detrimental to accurate typing. Apologies in advance.


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  # 1329822 23-Jun-2015 11:19
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Do you have condensation on other windows in the room / house?

And do you have it on these new ones?

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