Get proper double or triple paned windows or at least storm windows that are weather stripped. The best you can hopr for without those is insulated drpaes which only really work to keep the cold out if you keep them closed. There is a film you can add to the inside maybe check that out so at least you do not need to live in the dark all winter

I find the cellular pleated shades do a fairly decent job at cutting the cold down. I have used a custom insulated shade that worked very well. Only used it at night as it was opaque and if left on all the time, frost would build up on the window.

Where is the home? Using drapes or blinds to provide additional efficiency for a poorly performing window is going to be a double edge sword. You'll need to be wary of condensation and other issues that can manifest as a result of limiting heat flow to the window.

The home is in Vermont.

Get the plastic over the windows solution at a big box store. Hide the plastic by putting a sheer curtain between the window and the plastic. Also, get Warm Window fabric (a super insulated and quilted fabric) from a fabric store and have someone make roman blinds for you.

Plastic is your best bet and make sure it is well sealed.

Most efficient? External window shades.

External shades reflect the sun's rays away from the window before they have the chance to pass through the glass. Interior blinds trap the heat between the blind and the glass and therefore still impacts the internal temperature. The same principle applies to cool temperatures. The external shades are better able to regulate room temperatures in the winter to keep the heat in the home.

If your windows are insulated by external shades, they will not pull the heat from the home which is what causes the feeling of a "breeze" near the windows. Cold surfaces pull heat in order to regulate the temperature. If you eliminate the "pull" you eliminate the "breeze".

However, external shades are not decorative but purely functional.

Glo EW&D,

You might want to reread the original post.

Blocking solar heat gain is definitely not the point of the question.

oberon476 yes, wanted to post the photo first but was still formulating a full explanation of the benefits of external shades year-round ;)

In the short run, try temporary window plastic film that acts as an interior storm window like this: https://www.amazon.com/dp/B00002NCJI Fast, easy, effective.

In the medium run, add thick heavy lined curtains or install cellular shades. https://symphonyshades.com/ (in Vermont) makes great shades and has good customer service.

In the long run, have your windows tested to see how much air leaks through (see This Old House for quick DIY tests) and how readily they lose heat (a thermal imaging camera is used by pros). Then consider replacing the windows if they are not double-paned.

See this article: https://www.hunterdouglas.com/stories/insulating-shades

I have no affiliation with Hunter Douglas, but I do have these type of shades in my home. They definitely make the house more comfortable in the evening by reducing the radiant heat flow OUT to the nighttime sky. I like the clean look of these types of shades as well.

I have to agree with the other posts regarding the pitfalls of using window treatments in the name of cold weather energy savings. The insulating type products are indeed very effective, but the ensuing condensation caused by isolating your windows from the warm interior air is real and can be destructive. That moisture can damage the windows (depending on the material), the surrounding woodwork and walls, and in a bit of irony, the treatments themselves. This is not a problem that is necessarily imminent, but certainly possible. Window treatments for energy efficiency are somewhat of a band-aid for these reasons, the better and correct solution would be to upgrade the windows themselves, be it through replacement, storms, films, or whatever.

There's an interesting discussion related to this on a recent Fine Homebuilding post.

https://www.instagram.com/p/CIq8Is2HcH9/?utm_source=ig_web_copy_link

The consensus is maintaining original wood windows is preferable to replacement. But there are plenty of caveats.

if your budget is tight, the double celled pleated shades are your best bet. even better, combine them with heavy drapes (but be sure those drapes aren't above any kind of baseboard heater or vent, or the warm air will go under the curtains).

warning: like others said, moisture gets trapped under these things. I have to open mine every day just to air out the windows, they only get closed at night.

however, if you do decide to upgrade to double or triple paned windows, look into LoE glass. not only does it help keep heat out in the summer, this glass actually helps keep heat in during winter. it's more than just the air gap between the panes -- there's something about the glass treatment itself that reflects heat. so in the winter, that means it's reflecting home heating back indoors where it belongs.

The most energy efficient interior window treatments, according to the U.S. Department of Energy, include:

https://www.heatair.org/

Insulated cellular shades

Also called honeycomb shades, this is where energy efficiency meets style. These shades were introduced in the late 1970s in order to fill a need for window treatments that would reduce consumers’ energy use, following the energy crisis. Cellular shades can boost thermal comfort by raises the temperature by as much as 5°F. They also act as insulation and protect your home from the cold with their unique, energy-saving design. Each honeycomb insulates pockets of air, which can provide insulation. They are one of the best choices for window coverings, as they also offer optimal light and temperature control. The energy savings, though, are really a huge benefit both to your comfort, not to mention your wallet.

https://www.newcentralairconditioner.com/

Roller shades

These are among our most popular window treatment options at Bloomin’ Blinds. They are a solid insulating option and come in light filtering and blackout options for light management. The blackout option, which is also called solar shades, features opaque material that still allows for an outside view.

Roman shades

These beautiful, traditional shades have gorgeous fabrics and custom folds. This is a great option if you’re looking for light management, and the shades can be made of many types of materials, from heavy cloth fabrics to wood, or natural materials and fiber products. Heavier fabrics typically offer better thermal performance and are effective for privacy, blocking sunlight, in addition to room darkening.

Blinds

Whether they’re vertical or horizontal, blinds are effective at keeping heat out. They can reduce heat gain during the summer and effectively block and reflect direct sunlight onto a light-colored ceiling that will diffuse the light and allow you to take advantage of the natural daylight.

Draperies

These are a type of window treatment that reaches all the way down to the floor. Their effectiveness at reducing heat loss or gain depends on the fabric type (open or closed weave) and color, making it more difficult to generalize about their energy performance. However, studies show that medium-colored draperies with white-plastic backings can reduce heat gains by 1/3rd, and in cold weather, draperies can reduce heat loss from a warm room up to 10%.