Good morning Elena, You have asked a very big question. At first I was going to suggest one of the curtain rods that swivel back and forth, but that won’t work with what you want to do. The other option would be to install a small track on the ceiling and curve it around to enclose the vestibule. With this, I think, you could pick any fabric you like. IKEA has something similar, but it has limits in how it can be configured.

Years ago I lived in a 1910 shotgun house with very drafty window. So I know how it feels to have your heat escape.

Good luck to you.

I wonder if any of these ideas could be adapted? http://www.apartmenttherapy.com/ways-to-fake-a-canopy-bed-168372

I wonder if you hang a rod or wire mount from the ceiling perpendicular from the narrow wall where you've got that little ornament? Perhaps a heavyweight velvet or other more weather/stain resistant option. You could mount a tie back for it so it drapes nicely. Even though it wouldn't completely cover the stairwell area, the thicker fabric would block the opening and absorb a significant portion of the chill.

In the warmer weather, you could swap it out for a muslin or other decorative sheer so the curtain rod/wire doesn't look empty.

For the stairwell, you could weave a decorative fabric between the spindles to insulate. If you knit, perhaps an extra long 'scarf' would look interesting woven in there. It could be a wintery decorative touch. If you're into holiday decor, maybe some evergreen boughs?

These aren't fantastic solutions, sorry! I agree, you do have a tough angle to contend with. I'm interested to see some more suggestions too, I have a similar entryway.

Good luck!

What about installing two or three swing rods that way it automatically opens when the door does so you don't have to worry about having to fix the curtain every time someone enters.

I think Spacesha is on track. You could have a curtain go from the corner of the wall on the right in the photo (next to the door) and run it perpendicularly across to the stairs, have it make a right angle and run all along the stairs, that way you don't have the draft go up and it would look a little more finished when you came in the door. That would almost create a little mudroom which could be nice too. I like Spacesha idea of using a heavy fabric and having nice tie backs.

It's not ideal, but curtain solutions generally aren't!

If you want to run them in the L shape as I described, Ikea has a good ceiling mounted option (the Dignitet). I know you don't want to mess up the ceiling, but it would only need to be drilled in three spots (two end posts and one corner post), which would be easy to patch if you want to take it down in the future: http://www.ikea.com/us/en/catalog/products/60075295/

How about something like this:

http://www.signaturehardware.com/product2734?utm_medium=shoppingengine&utm_source=google&utm_content=Bathroom-Shower%20Rods%20Rings&adtype=pla&gclid=CNWMqO_E4LMCFQSf4AodVGsA1Q

if you're in a really cool climate, you might think about walling off that small foyer and creating a double-door entry (think: airlock). you're really only feeling the cold at the floor because of the cold air sinking to the ground (and you likely have heat registers in the ceiling which isn't helping floor coolness.

thinking about it from the opposite direction, how about adding a bit of heat to the floor in the form of an under-rug heating pad?

in our home, we have radiant-floor heat and never have a cold floor. if the house was more insulated, it'd be ideal. however, we have one room where the heat doesn't work and were thinking about something like this: http://cozywinters.com/shop/rug-heat.html

Use pluming items such as a flange (on the ceiling) small piping to come down from the ceiling to support your "rods". Use an angled "Y" to run piping to the walls. pvc comes in white, you can easily sand off any blue writing on the pipe (or paint them if desired). Then you could basically hang any curtain, or shower curtain int he space in both directions (across the stairwell side, and another set in the entrance side).
Not sure if that description works without a picture to show you. LOL

plumbing*

That space looks a little tight with the closet door and stairs nearby. Have you considered buying/building a temporary winter vestibule like restaurants use? If you buy it in red, it can blend in with holiday decorations.

Here are some examples:
http://tinyurl.com/av38x45

Another idea is to put a flexible room divider there. Even if it doesn't reach the ceiling, it would still prevent some of the cold air from entering. This one is solid, pretty tall, and flexible:

http://www.chiasso.com/store/item.aspx?ItemId=50514

With crawling babies, you might not want it to be freestanding, but you could probably thread some wire or string in between the thin slats to attach it at multiple points to the banister, leaving the end facing the living area free to swing open and closed. You could also glue on some strong magnets or use strips of velcro to make it more secure when closed.

I think you should explore non-curtain solutions, for example, do you have a storm door? Have you checked to see if your door needs weather stripping?

I like that temporary vestibule idea. Here's another link to check out: http://abris-saint-jerome.com/en/shelter-services/storage/vestibule-51-in-of-width-temporary-shelter-storage/

Born and raised in Ireland, it's very common for a home to have a heavy curtain in front of a door because of inclement weather and drafts. Works like a charm!!

I think those who say you need an L-shaped curtain are right. One from the little wall next to the door over to the stairs, and the other from there in front of the stairs over to the closet. Do not use ceiling track, too institutional. Do not use wire, which is what I think that Ikea solution recommended is - you want heavy material, and I think wire is best for lighter material. Rather, Get some strong curtain rods - I'm seeing metal ones, at least a half inch thick, which nice, but relatively small finials. Then, get the brackets for hanging the rods that attach to the ceiling. They can be two completely separate rods, that just happen to meet around the stair corner there. Then hang two curtains. There'll be an opening where they meet at the stair corner for entering and exiting. Should work well.

@LeahB @ValHalla

The problem is when the door is open.

What about a folding screen? The kind that sits on the floor and has hinges. You could make one with padding and insulation. Then you can move it out of the way when you don't need it.

I agree with some of the above commenters. use plumbing. Copper plumbing is inexpensive at home depot, and if you mount hooks from the ceiling you can use pipe and elbows to create a u shape to hang from the ceiling. i use the 1/2 in copper pipe as my normal curtain rods in my apt because it's cheap and they look super cute. The copper pipe looks like it might be flimsy holding curtains, but it isn't.... and you can just cut three lengths of pipe, use elbows to connect them (you can use super glue in the elbow if you're concerned it won't hold without soldering.) and voila! and you don't have to be worried about ugly plastic pvc.... 1/2" by 10 feet is only 12 bucks! http://www.homedepot.com/Plumbing-Pipes-Fittings-Valves-Copper-Pipe-Fittings/h_d1/N-5yc1vZbuu2/R-100354198/h_d2/ProductDisplay?catalogId=10053&langId=-1&storeId=10051#.UK8EeIXXdL8

I hate to refer to a movie (and I can't find a photo online), but if you've seen "Taken"/Liam Neeson - the former french field agent whose home he visits for dinner, Jean-Claude... take a look at the front door to his apartment when he enters. It had a beautiful (velvet?) curtain hanging over it and I remember saying, wow that's a really good idea!

Ah-HA! It's called a "portière" (same word for a car door) but an image search for "portière curtain" brings up some nice examples: http://tinyurl.com/ct3yt4f

^ Interesting images and some attractive ideas. One of the photos leads to a similar older question on AT: http://www.apartmenttherapy.com/a-curtain-at-the-front-door-141160

@keltrue Great examples! we did something similar to this example from you suggestions. The curtain moves with the door. http://www.flickriver.com/photos/chailey/sets/72157603289890652 But... it just keeps drafts out. No matter what you do, when you open the door cold air comes in, warm air goes out. Even if you build an enclosure this will be true. Take it from someone who lived in far north MN and MI for 30+ years!

Something like this could work http://www.urbanoutfitters.com/urban/catalog/productdetail.jsp?id=18904243&parentid=A_RUGPILCUR