Different glass types - what's the real deal?

[Mark]

I was visiting Cardinal Glass' website, www.cardinalcorp.com, and saw that they have 4 different types of glass:
LoE2 - 140 - All Climate glare control - cool & consistent for glare & solar control
LoE2 - 170 - All Climate solar control - the best in solar control without tinting
LoE2 - 172 - All Climate, all season - the clear glass choice for year-round comfort
LoE2 - 178 - Winter Climate - comfort glass to keep you warm

I presume that other glass manufacturers have similiar types.

Now when I had all the window salesmen through my house NOT one of them ever offered me a choice of glass type, nor did any of them ever mention that their window manufacturer had chosen the best glass type for my city.

1) Does the different types of glass really make a significant difference?

2) Why don't salesmen ever mention it?

3) Do the glass companies automatically chose the most appropriate glass type for where I live?

4) Without specifying the glass type in a contract, does that mean that I am going to get the cheapest glass type possible (which probably means not optimal)?

5) What is the optimal glass for Atlanta?

6) How do I find out the glass types that Schuco uses?

[Greg]

Generally the different manufacturers that use Cardinal choose the type that it is optimum for their climate area. This means that you don't have a lot of choice without paying a little more for a glass that performs a little differently. The easiest way to decipher the numbers is to think of the last two " 1 -70" as the amount of visible light emitted by that type of low e. The higher the number the more light. If you are in a colder area that is good. A warmer area probably wants a lower number. I have over simplied it a little but I hope this helps.

[deringer2]

There is big difference in the "color" of the glass, AND, I think the amount of reflection at nighttime; all a matter of personal preference perhaps, but a fairly expensive surprise if you are expecting the same glass that you had originally. Also, you might want to ask about Cardinal's easy-clean coating since I think many (well, some, anyway) manufacturers are including this at no additional cost -- a nice little bonus if you ask for it.

[earwax]

The 140 is a blue tint that is very noticable. NOt very residential windows manuf. use this. 170 is more common and 172 by a few. I personally prefer the 170. IT is the most common in my area, and thus, if it ever needs to be replaced out of my own pocket, it will be ealy to do.

[Oberon]

I may be picking nits, but the comparisons listed in the original post are for different versions of LowE coatings and not different types of glass.
I realize that most of the regulars here understand that, but new, and as yet uneducated, folks might be confused into thinking that there are different types of glass available based on the comparisons.