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.

Picture of house with East facing prow

  • 2
    We're not a discussion forum, so I've removed the friendly (but distracting) chit-chat. Sure, new windows would help insulate, but more effective by far might be reflective film. Window insulation value is probably more effective in winter. It's hard to say without a total structure energy assessment. I would definitely not close up the windows. That would be a real tragedy.
    – isherwood
    Commented Jun 25, 2020 at 23:38
  • Thanks. I was hoping it was appropriate here, but I guess not. I respect your decision and look forward to continuing to participate here. I love this site. Commented Jun 26, 2020 at 0:10
  • That "prow" was definitely the look for a while in the 80s. It definitely dates the house, but it's appropriate. Closing some of them off (boarding them over, even if done to match the exterior, not just slapping up plywood) will significantly alter the look of the house, increase the need for interior lighting during the day, and potentially impact resale value in the future.
    – FreeMan
    Commented Jun 26, 2020 at 12:11
  • 1980's is probably before the advent of "Low-E" windows, as far as I recall - ie, the double panes from that era are just double panes. Replacing with windows specifically chosen for a low Solar Heat Gain Coefficient (SHGC) should make a significant difference, but will also be costly - however, if the seals have failed and the windows need to be replaced anyway, not a large increase (if any) in cost.
    – Ecnerwal
    Commented Jun 26, 2020 at 12:15

2 Answers 2


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:


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.

  • Because links die, can you include some highlights from the linked site, please.
    – FreeMan
    Commented Jun 26, 2020 at 12:08
  • @FreeMan I disagree with the concept of reiterating the content of an article in an “answer”. My answer is for the OP, not for future reference in two or three years. My answer explains what is possible without picking Solar Gray or Solar Bronze coating. Likewise, I’m not explaining why Side 2 of the double pane system is best, I’m just letting them know there are options where the coating can be applied. It’s their responsibility to research what is available in their region and determine which is best for them. I know I’m not popular with this concept...
    – Lee Sam
    Commented Jun 26, 2020 at 14:53
  • Not popular and against the SE rules on referencing external sources. I'm not gonna down vote or flag because the other info in the answer is very good. Just pointing it out.
    – FreeMan
    Commented Jun 26, 2020 at 14:58
  • @FreeMan Oh boy...I can downvote everyone who provides a link and does not provide the name of the original author. (That’s silly.)
    – Lee Sam
    Commented Jun 26, 2020 at 15:41

Get roller blinds with appropriate fabric, here it is called finescreen. Lets light through but blocks the sun/heat. That will definitely cover the rectangular portion of the window.

For the triangle part at the top talk to blinds specialist, they might have a solution plus measure and quote are free (where I live). At least get a blind where it fits and cover the rest with the same fabric as DIY.

  • Blinds inside do very little, as the heat on the blinds is still inside the conditioned space. An awning or shade cloth OUTSIDE the window can help a great deal.
    – Ecnerwal
    Commented Jun 26, 2020 at 12:11
  • A correct blind will stop the heat going into the room. I worked at manufacturing blinds and seen them in use. Incorrect blind will do very little.
    – anm767
    Commented Jun 27, 2020 at 6:08

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