Window glass U-value 0.7 W/m² K vs. 0.75 W/m² K

  • Erstellt am 2014-11-26 12:27:53

Fantamoax

2014-11-26 12:27:53
  • #1
Hello dear community,

An ignorant person going astray.

I am currently dealing with the question of whether improving the material of the window surfaces is really worth it. I know, this is obviously also a small look into the crystal ball. We have quite a few floor-to-ceiling window elements. The wide south side is almost completely glazed. Wall construction 24 cm bricks, 18 cm external insulation (also a matter of belief but not our topic)

We are installing the Brügmann Bluevolution 82 profile. The offer would be an extra 1500 euros for all windows. That means that with an estimated service life of 20 years, I would have to save about 80 euros per year. The extra cost seems reasonable to me, nevertheless we are still hesitating a bit, since we have already ordered this or that... 500€ 1000€ here...

It’s gradually adding up...

How do you see it, would the effort pay off? Or am I already doing sufficiently well with my standard windows...

Best regards

Ps: If interested, we can also discuss window insulation in general in this thread
 

Fantamoax

2014-11-26 12:29:24
  • #2
Oops, headline wrong of course 0.50 W/m2 K
 

nordanney

2014-11-26 20:01:07
  • #3
How does the U-value of the entire window change? Then the consideration might make more sense.
 

Fantamoax

2014-11-27 04:49:37
  • #4
The window changes from 0.89 to 0.76 with the standard window.

However, since we have many large glass surfaces (many floor-to-ceiling elements 2.50m), I thought that the value of the glass is actually more meaningful.

Best regards

Fanta
 

Saruss

2014-11-27 10:56:01
  • #5
So you save 0.13W per sqm of area and 1° temperature difference. So you can roughly calculate how much heat energy is lost with the average temperatures during the heating months, e.g. per day at about 0 degrees outside: average difference inside-outside 20℃ results in 20*0.13W/sqmK=2.6W per sqm, so per day 2.6W*24H=62.4Wh=0.0624kWh per sqm. For maybe (you save with information!!) 15sqm that is 0.936kWh of heat energy, with an efficient heat pump maybe 0.2 to 0.25kWh of electricity, about 7 cents for the day. If now each of the 150 days of the heating period is this cold, 10€ per year. But I do not know your indoor temperature nor all other data, so the estimate is only rough. So you can estimate what this saves with the temperatures in your region in recent years. Whether the comfort increases because of less cold inside at the windows, I also dare to doubt with these values. Much more often a thicker frame brings more than just better glass.
 

Fantamoax

2014-11-27 12:19:20
  • #6
Thank you very much for your detailed response Saurus!!

Sorry if I have been stingy with information. I thought the data was already sufficient, of course a lot depends on the heating and the rest of the insulation.

You have definitely helped me a lot in my decision-making.

If I should perhaps add more information for others, just write briefly which data I should add.

I will probably stick with the 0.7 glass, the savings actually seem too small to me..

Best regards

Fanta
 

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