I was wondering about something like this set up for dealing with excess heat. Maybe it could be adapted for cold?

Double plastic, inside and out, with a layer of ziplock freezer bags filled with just enough water to make a thin layer of water in the bag, taped to the inside of the innermost plastic. Repeat layers as needed.

It might not work at all, and might be way expensive, but maybe it wouldn't be too heavy?

Eh. I have NO experience dealing with the sort of cold you deal with.

One other idea-- what if you double layered the plastic, inside and out, then blew the hot air from the heaters into the double-layered plastic space only? If you kept that tiny space warm, would the rest of the porch remain warm enough? Would this be a fire hazard?

Thank you merrybookwyrm! Too bad you cannot just send me some of your excess heat; I will send you some snow in return.

I like the idea of the bags of water. I've convinced my husband to try one more year; we're going to plastic inside and out, try bubble wrap and heavy draperies over the two ends (they're only a few feet wide, don't get direct sunlight and it's where the wind tends to be worst).

Really what we need are new windows, but almost the entire sunporch consists of these great old six feet tall windows made up of small panes of single pane glass and it would probably cost a fortune if we could even find suitable replacements that maintained the old-fashioned appearance.

I wonder if I kept water right around the plants if that would help too? I think I'm going to try it! Most of the plants are on shelves under the windows and a nice black plastic bag filled with just a bit of water could go beneath them. That should help them - the poor plants; keeping them alive is about the best I can hope for.

Thanks for your suggestions - it really is so nice to be able to sit surrounded by plants in the dead of winter.

oh, bubble wrap! Good idea. That brings to mind styrofoam. What if you cut styrofoam ice chests into panels, taped them together into a flat surface, and put them in the windows that are going to have heavy drapes, too?

Sometimes, it would be nice to trade heat and snow. The temptation...

go to a home depot or building supply. Look at the cost of the styrophone panels they put in walls. Some even have aluminum backs. My experience with these have been good when I used them to cut down and cover large windows in the winter to keep out cold and air. You might use them on the ends and under and over the sunshine windows. You could cut them up also to go over bottom of windows, giving a bit of coverage to the jams that leak. And on top if that is where the air comes from. Just cut with a serated knife or a razor cutter. I put some of mine in 'pillowcases' of material since they were visable from street....the rest I just put in. I cut them a speck larger and forced them into window and just put duct tape on them to hold in place and seal out more air. Just watch for places that can sweat and cause mildew....but 2 tables spoon of water in a gallon of water can eliminate that

The styrofoam would be great too as an additional night-time protection. The first year we were here we made it through most of the winter; then one night the temperature dropped about seven degrees colder than they were saying it would (to about -5) and we lost half the plants overnight.

I'm wondering why we never just completely blocked off the ends before and I realize it's because we do it in the fall and there is a gorgeous sugar maple that can only be seen out the end - must have been why we kept leaving the view unobstructed. Of course in the winter it isn't very spectacular.

Bubble wrap - ruins the view, but it insulates nicely.

Build a couple of panels of exterior-grade sheathing (maybe even attractive exterior sheathing) to block off the ends and insulate the panel on the inside with really high-R foam insulation ... if you were trying to heat the place with huge gaps at the ends, no wonder your bills were high!

Insulate the underside of the balcony if you can get at it, if not, build a sort of deck and put insulation on the balcony floor.

As soon as the maple drops its leaves, plug the hole.

With the ends blocked, you may find that it gets plenty warm in there during the day and you can open the door and use it as a solar space heater.

LATE COMMENT, I KNOW, but maybe it will help someone—- I recently saw the following hints: A). “Rigid Insulation” placed inside outside pots is recommended by This Old House. Maybe it would also work on the lower parts of your windows….. B). There are claims that Non-LED Christmas lights can generate enough heat to keep plants alive….. Obviously you would remove any flammable materials near the lights:…. C). “Pool” Bubble Wrap is supposed to be a better insulator than “packing” bubble wrap….. D). While Heated Plant Grow Mats are typically used to germinate seeds, some claim that they will produce enough heat to keep your plants alive…. E). If you’re going to use supplemental heat, per a friend who is a heating and air business owner,, those oil-filled electric heaters that look like radiators are supposed to be the safest.. Obviously all products should be manufactured by reputable companies and should be checked frequently…. F). Dehumidifiers also generate a lot of heat…. Don’t forget to regularly empty the buckets of water if your humidity is high….. G). If you must bring your plants inside, Grow Lights may help you keep them alive… H). Larger pots are considered more insulating than smaller pots….. I). Glass or plastics cloche (covers) for each pot might be a consideration.