Picture window letting in a lot of heat???

[dorriP]

Is this normal? We had our old style replaced a couple of weeks ago, and when the sun is setting, it does cause our furniture to get pretty warm? It's a tri-pane low e argon glass. The other windows in our house are more expensive and they too let in the summer sun even though they said they are supposed to let less heat in. I'm not so sure about that one? They all do to some degree. Guess it will be welcomed in the winter, but hope they don't let the cold in the winter? What's your experience with tri pane, low E argon gas, anyone?.

[ssbtech]

Were they low-e hard coat or soft coat?

[dirtmover]

There are different parameters that define how well a window performs overall. You are experiencing solar gain which is a good thing in the winter but not necessarily in the summer. Insulation effectiveness (U-factor) is the parameter you need to be concerned about for letting heat transfer through the window. With triple pane argon you should be fine.

Ideally in our climate you want high solar gain and high U-factor combined with some method of blocking the sun in the summer. This would typically be deciduous tree coverage or overhangs that block the high summer sun. A good designer will even recommend different parameters depending on what direction the windows are facing.

[dorriP]

Thanks, the window is on the west side and we do have a bit of a roof over hang but when the sun is setting it has a way of coming down under it. We need to find good window covering as well that will block some of the heat when we want it.
If I'm understanding this right, a standard insulating glass has a uv of 58% coming in while ours has a uv of 48% which means a little less harmful rays coming in, that's if I'm understanding the diagram I have right.

I have no idea if they were a low e hard coat or soft coat? It doesn't mention this anywhere?