ᐅ Double or triple glazing in new construction – triple glazing allegedly an unnecessary expense
Created on: 23 Sep 2022 09:54
S
SmeagolHello everyone,
The window salesperson/advisor recommended using double glazing with a U-value of 0.81 instead of triple glazing with a U-value of 0.6 for our new build at KFW60 standard.
The additional cost for the nearly 17 windows and patio doors totals around 3,000 EUR.
They explained that triple glazing reduces solar heat gain (which makes sense due to light refraction and so on), but still suggested that the extra expense might not be worth it. Online, I found a break-even point of about 10 years for the additional cost of triple glazing.
What’s your assessment?
Thanks!
The window salesperson/advisor recommended using double glazing with a U-value of 0.81 instead of triple glazing with a U-value of 0.6 for our new build at KFW60 standard.
The additional cost for the nearly 17 windows and patio doors totals around 3,000 EUR.
They explained that triple glazing reduces solar heat gain (which makes sense due to light refraction and so on), but still suggested that the extra expense might not be worth it. Online, I found a break-even point of about 10 years for the additional cost of triple glazing.
What’s your assessment?
Thanks!
S
SaniererNRW12323 Sep 2022 11:33kati1337 schrieb:
Is KFW55 now the standard and also mandatory? Since 2023. KFW60 has never existed.
Smeagol schrieb:
The window salesperson/advisor recommended, in response to our request for a new building (KFW60 level) with triple glazing and a U-value of 0.6, to rather install double glazing with a U-value of 0.81. Question: How does the advisor achieve a U-value of 0.81 with double glazing? If that’s possible, then using double glazing could be considered safe. I have no idea how that works. Many triple-glazed windows have worse values.
It really depends a lot on where sunlight actually enters in winter and how much. The window salesperson probably hasn’t calculated that precisely.
If you go into detail, you can also consider factors like comfort from radiant heat. Double-glazed windows emit more cold radiation than triple-glazed ones, meaning you have to heat the room to a higher temperature to feel the same comfort. You can get lost in details if you want.
Or you could factor in the interest on the 3,000 euros and compare that to potential energy cost developments, and so on.
But it simply doesn’t make much sense to try to save a few thousand euros here. The additional heating costs alone will probably be around 50 euros per year at the supply temperature… If you really have to watch every euro, sure, you can save that, but then you should also consider whether everything is still okay if you have to focus on saving 3,000 euros.
If you go into detail, you can also consider factors like comfort from radiant heat. Double-glazed windows emit more cold radiation than triple-glazed ones, meaning you have to heat the room to a higher temperature to feel the same comfort. You can get lost in details if you want.
Or you could factor in the interest on the 3,000 euros and compare that to potential energy cost developments, and so on.
But it simply doesn’t make much sense to try to save a few thousand euros here. The additional heating costs alone will probably be around 50 euros per year at the supply temperature… If you really have to watch every euro, sure, you can save that, but then you should also consider whether everything is still okay if you have to focus on saving 3,000 euros.
Ok, ok, there was definitely some confusion with the Uw and Ug values, sorry about that.
I deliberately mentioned the KFW60 level because the house’s energy consumption corresponds to that level. Let’s set aside the canceled KFW subsidy, which we weren’t going to receive anyway.
And no: it wasn’t about the last 3,000 EUR. On the contrary, I was actually fully convinced to go with the triple glazing, but the consultant himself said it doesn’t really make much difference overall. I was quite surprised by that. I will ask to have the technical data sent again to get a more precise evaluation.
The four large floor-to-ceiling units are facing south, but as you’ve already mentioned: the sun doesn’t shine every day!
He roughly estimated the heating cost savings at about 50 EUR per year compared to triple glazing. That’s why he suggested considering using that money for something else instead.
I deliberately mentioned the KFW60 level because the house’s energy consumption corresponds to that level. Let’s set aside the canceled KFW subsidy, which we weren’t going to receive anyway.
And no: it wasn’t about the last 3,000 EUR. On the contrary, I was actually fully convinced to go with the triple glazing, but the consultant himself said it doesn’t really make much difference overall. I was quite surprised by that. I will ask to have the technical data sent again to get a more precise evaluation.
The four large floor-to-ceiling units are facing south, but as you’ve already mentioned: the sun doesn’t shine every day!
He roughly estimated the heating cost savings at about 50 EUR per year compared to triple glazing. That’s why he suggested considering using that money for something else instead.
Similar topics