Retrofitting window in house for energy savings?

I am trying to find ways to make my house more energy efficient. We’ve got lots of windows, all of them old, none of them particularly effective at insulation. Obviously swapping them for new windows will help, but cost a fortune.

However, we’ve got several very large windows that don’t move at all (next to sliding glass doors which allow access to our balcony, but the windows next to the doors are about twice the size of the doors).

The windows are inset in wood frames in the house, and I believe there’s more than enough room to put another piece of glass in the frames with a centimeter or so of space between the glass panes. LIke a modern double paned window, but obviously I won’t be able to fill the space in between with insulating gas, it’d be full of whatever air was trapped there when the 2nd glass pane was installed.

If this is done correctly, will it effectively make those windows double paned, and therefore (much?) more energy efficient?

It will be more energy efficient but you will probably have trouble with condensation. Moisture will form on the inside fogging the glass.

Usually with old windows a lot of energy is lost from air leaking around the windows. If you really can’t afford new windows you can remove the molding and insulate around them to insure a tight seal with the house. Same thing with electrical outlets.

Oh, condensation is no good on the windows with an amazing view. Thanks for the warning. Not sure how easy it’d be to remove them an insulate around them without doing lots of damage to the wood, but I’m gonna go look right now. Thanks!

Get a bunch of those silica gel packets, and heat them to 200 °F for a while, then put them in between the two panes of glass - that will take care of your condensation problem for a while.

If this is just for winter, you can buy kits for just this purpose at Home Depot. It basically consists of plastic material that you put over the window, then heat up to expand the air between the window and the plastic.

I’ve done this to the windows in the front and side doors to my house. Used lucite instead of glass for the second panes, and transparent caulk to seal. I’ve not had any trouble with condensation between the panes, but ymmv.

Thanks, all.

Squink – did you notice a difference in indoor climate control?

Oh, yes! Adding a second pane to the side door increased the habitability of the unheated basement markedly in winter.

Good to know!