A website that allows you to calculate the true performance of windows

Today's content is purely for practitioners...
The insulating performance of Japanese windows is expressed by an index called the U-value.
However, the way it is displayed is extremely sloppy.
In reality, each window is different, but the values are usually less than 2.33, less than 3.49, less than 4.65, etc.
The stages are simply divided into fairly broad categories.
In terms of a car, the most important fuel efficiency reading is 23.3km/L, and the next reading up to 34.9 should be treated the same.
It's such a rough division that it's almost funny.
Moreover, even though it is said to be below 2.33, when you actually calculate it, it may exceed 2.33.
The reality is that it happens so often that it makes things even worse.
If you use the Building Fuel Efficiency Navi, the performance of each individual sash will become immediately clear.
If you don't have one, you can still calculate it on the website below.
http://w3.metds.co.jp/WindEye
I think it's a very well-made site that's free and publicly available.
I played around with it to see how the performance of windows differs depending on the opening style and dimensions.
I encourage you to do the math, you'll be amazed at the difference.
but···.
It would be too tedious for practitioners to calculate each window and use the data.
It's almost impossible.
It's safest to use a building fuel efficiency navigation system.