A friend of mine is remodeling his 1980s house and was asking advice about keeping it cooler in the summer. The house currently has the original double pane windows, many of which have "popped" and are clouded. The house is east facing and gets tons of morning and early afternoon sun. It gets really hot during the day in the summer. It doesn't currently have any A/C. It's heating system is a wood stove and old fashioned baseboard heat. He's thinking about a mini-split system for heating and cooling, but I'm worried that it will be expensive to run the A/C unless he deals with the solar radiation heating the house.
One thing I suggested was to close off some of the upper windows in the prow, insulate and drywall over the openings. That would change the look, but might help control the solar radiation.
Another consideration is how much additional insulation could be expected with replacing the windows? How much difference could that make? Again, they are double pane, but now about 35 years old.
Best Answer
Different types of solar coatings (and where they are installed on the glass panes) can make a significant difference in the amount of solar gain.
There are various types of solar coatings and each serves a separate purpose. However, they all allow vision out the glass.
You indicate some of the double pane windows have failed. I’d take this opportunity to replace the glazing units with special solar coating. Here’s an article that explains the various types:
https://www.google.com/amp/glassed.vitroglazings.com/topics/how-low-e-glass-works%3Fhs_amp%3Dtrue
In addition to the various types of solar coatings, there are 4 surfaces to a double pane window where the coatings can be applied. Installing it on the inside surface of the exterior pane will provide best reflection.
This process needs to be accomplished by a window manufacturer, but you do not need to remove the window frame, just the glazing.
I’d do all the panes so all the windows look the same when viewed from the outside and inside.