U glass - Advice in definition

grasshopper honeybee-legacy
1

Hi,
I’m wondering how you, gurus on radiance, recommend to define this type of glass.
Is not exactly a brick glass, and also they can have different properties (according to type). It can be “single” layer or double.
From the above site i can get only VT and U value, but i’m sure that this is not a regular glass. Should it be a “trans” type?
@sarith or @mostapha: any ideas?

Thanks,
-A.

2

Hi @AbrahamYezioro, I dont have a definitive answer for you. Since this from Saint Gobain, easiest thing to do would be to ask them. They have a dedicated team of researchers either in France or the US. I just tried a test with dielectric and it didnt match the images on the website. Over the years there have been numerous presentations on the topic of glass modeling in Radiance workshops. Andy’s presentation from 2015 might be worth looking into. Also this.

3

Thanks @sarith,

I’ll check more in detail the links you suggested.
Still, if you happen to have more ideas, bring them on.

Thanks again,
-A.

4

Hi Abraham,

Depending on what you’re trying to measure - you might be able to get away with just modeling a normal glass material with the correct VLT. If you’re only looking at daylight penetration (sDA or similar metric) than this would work (not perfect but would give you a good idea of how much light will enter the space).

However, if you are interested in studying glare or would like to create a more realistic rendering, than you would have to use another material definition… likely a trans material or some sort of BSDF material definition. Honestly, this is a very tricky thing to get right so as mentioned earlier, I would definitely reach out to Saint Gobain for some guidance.

5

Thanks @MariaGrimm,
Indeed tricky. That’s the reason i asked here :slight_smile:
Already approached Saint Gobain, but unfortunately, so far, no response from them.
-A.

6

Hi @AbrahamYezioro, do you have access to this material or a non-touched up image of a location where it is installed? In case there is an unbiased idea about how this material actually behaves, we might be able to build something using the Glaze script.

7

I would second @MariaGrimm. This looks like a case for BSDF. @AbrahamYezioro, in LBNL Windows, if you can assemble a glazing system close to this product then you can export BSDF in .xml. Once, that is done, you know what to do. Also, as @sarith recommended, directly ask them if they have BSDF for this product.

8

Thanks @sarith.
This is the story of this tread:
Our faculty is about to build a small “pavillion” which was designated to some architect. This is a donation, and as expected the budget was miscalculated and the university is looking how to “save” money.
We are talking, from the building point of view, of practically a glass box (!!) (Disaster).
The last move of the architects is to propose this U Glass, but thei proposal is so vague that i can’t provide any details of the properties of the glass. The provided perspectives are also “vague” in content (and can’t be published). The pavillion is a box where the long sides face NorthWest and SouthEast directions.
I’m trying to make some tests in order to prove the possible glare problems (not to say thermal conditions inside).
As i said before, i didn’t get any answer from Saint Gobain, unfortunately.
I’ll try to ask the architects to provide the details of the glass they intend to use.

If they don;t, i"ll take the worst and best i can identify from the website, which is a lot of speculative way … :frowning:

Thanks again @sarith and you too @devang.
-A.