What our research found: Pyrolitic or Hard-Coat Low-E coating are designed to reduce heat loss and to increase solar gain. This is great for areas needing a lot of winter warming and not a lot of summer heat. The SHGC is normally higher for this type. We were told that this is the older Low-E coating. Sputtered or Soft-Coat Low-E are designed to reduce heat loss and let in some solar heat, not as much as pyrolitic. This is OK for areas where there are both heating needs and cooling needs. Still good for cold winter area and mild summer area. This is Low-E II. Spectrally Selective Sputtered coating Low-E are designed to reduce heat loss in winter and also reduce heat gain in summer. THis is for area where we have cold winter and real hot summer. Another version of Low-E II. In Texas, I would definitely go with Low-E II, it is a no brainer. We live in CA where it gets downright cold, blasting rain and some snow and then searing hot summer. Low-E would have been insufficient so we have Low-E II. The difference in temperature, depending on insulation in the house wall, can be dramatic. We often are a cool 70-F inside while it is 105-F outside.

Using tempered glass will help protect your window from heat related stress breakage - I suspect that the window company that suggested tempered glass was considering the possibilty of an after market window film and they realized that you would need tempered glass to avoid future heat-related stress problems. Using LowE is not an option, it is a necessity in your (or any other) environment. The primary consideration being what LowE coating to use in what environment. As mentioned, you do not need supplemental interior window film when you have a LowE coating...in fact, once again, it would be a very bad idea to do so when using annealed (non tempered) glass because of potential heat stress problems. As I mentioned in my earlier post, it is very unlikely that you will ever notice a color shift under normal viewing conditions when using a LowE coating. It really is a non-issue - LowE coated windows do not have a noticeable tint in transmittance (when looking thru the glass). Since your window faces south you should consider a couple different options (in addition to the solarban 60) when it comes to LowE coatings. Solarban 60 is a "LowE2" coating. That means that it has two layers of silver in the coating. Silver is the operative element in a LowE coating. LowE2 is considered to be a moderate solar heat gain coating. A LowE3 coating (LoE-366 mentioned earlier as an example) has three layers of silver in the coating and is considered to be a low solar heat gain coating - meaning very little solar heat will get thru the glass - summer or winter. In addition to the two and three silver layer coatings, there are also coatings that are considered to be high solar heat gain (a couple different types, including single-silver layer coatings). In a heating-dominated environment, a high solar heat gain coating on south-facing glass may be your best option because in the winter it is going to allow some very welcome heat into your home. The downside of course is that it will allow more summer solar heat gain than will either of the other two options. Solarban 60, as a moderate solar heat gain coating, will allow less solar heat gain in both winter and summer...but it will still allow some winter heat gain which is usually very welcome. How high up are you?

We used the same combination of windows in our house, it has worked out quite nicely. The windows look odd without the spacer bar, it is definitely a worthwhile addition and the efficiency cost is pretty minimal. We had no problem hitting better than stretch code energy requirements with these windows. The U factors for the Integrity windows seems to be the same with and without spacer.

orveusz, You are welcome. I89 is an exposed surface 4 coating. What it does is reflect heat back into the room rather than having the glass absorb that heat. Reflecting back into the room does two things: 1) it makes sitting next to the window more comfortable because the air in front of the window is slightly warmer. This also results in improved U value performance (less heat loss through the glass) 2) because the glass isn't absorbing room heat, the glass is colder than it would be otherwise and this can potentially lead to increased condensation on the window glass if its really cold outside...you know like mid january in Minnesota. Some windows companies are more concerned about this potential than others, and some add disclaimers about this possibility. As I recall, testing by Cardinal has shown that I89 is going to lower edge glass temps about 4° or so, and center of glass about 9° or so versus not using the I89 coating. Is that a problem? The simple answer is...it depends. Primarily it depends on how cold it is outside and how much moisture there is inside. If someone is in a moderate climate then it simply won't be an issue. If you live in Minnesota in January then you might notice an increase in window condensation on the coldest days. Keep in mind that using a warm-edge spacer helps a lot at the edge. In fact, using a warm edge spacer with I89 results in edge temperature that is still higher than using an aluminium spacer without the I89 coating. As to center-of-glass, 9° does sound like a lot, but even with that much potential glass cooling, with a LowE coating and argon fill the center of glass temp is still higher than it would be if all you had is a plain uncoated dual pane glass package. And even in the coldest days (bathroom windows excepted), how often does anyone see condensation over an entire window - assuming that the inside of the home isn't really humid. So will I89 cause your windows to be wetter than they might be otherwise? They might where you (and I) live. But even if it does, it might not be an issue more than a few days during an entire winter. Make sense?