If you can drill holes into the ceiling, you can have three hooks come down (each side and in the middle) that can hold a pole for a set of curtains.

I know you don't want to but just wanted to emphasize don't drill into the aluminum unless you like huge heating/cooling bills!

If you have the money I'd suggest big-a%% industrial roller blinds.

Could you suspend a track from the ceiling? I'm thinking something like dignitet or kvartal. http://www.apartmenttherapy.com/ny/materials-misc/dignitet-hardware-from-ikea-000985 or

PS can you use Tapcon fasteners for concrete in this kind of application where the stress is tension forces?

I would suggest bottom-up shades. The system can be installed between the top of the brick sill and the ceiling without touching the windows themselves. The look is a bit industrial, but I think it would fit with the space well.

I would just install frosted window film over the windows. It would still maintain the industrial look and allow light through, but still block people from seeing inside. Home Depot sells it under: Artscape Decorative Etched Window Film, but I'm sure you can find it for much less elsewhere.

I've seen some curtains on Apartment Therapy that were hung from a pole set at the top of a tall space, with chains hanging down to hold curtains that started about halfway down the space. Maybe someone here knows where that picture is. That might be possible.

What is directly above the window? I'm having a hard time seeing where the ceiling begins. What is that white thing (a/c?) in upper right attached to?

Thanks for all of the comments--very helpful!

@nekopan, the window goes all the way to the ceiling, which is also concrete. The white part in the upper right is also part of the ceiling.

@robotropolis thanks for the tip on concrete screws, we'll probably have to go that route and hang down from the ceiling. If we end up not being able to do that, the frosted window tip from @DanielleEsq is also great!

Just as a side note-would have loved to just do bottom up shades but the window sill is sloped ~45 degrees

Thanks everyone, will keep you updated on the final product. Feel free to leave more ideas.

How about placing multiple dressing screens in front of the windows.

I used to live in a loft with similar windows. I had very long rolls of a silver tinted window shade. From the inside, it helped cut the brightness while retaining full visibility and the full view out. From the outside, the reflective nature helped block out most of what was going on and gave me a significant amount of privacy. I didn't install it, so I don't know the exact manufacturer, but here's an example: www.northsolarscreen.com/html/display.shtml

oops, forgot to mention: I would suggest using 3 shades that hang from the rollers at top (that's how mine were). The only downside- they're likely to catch in a strong breeze when next to an open window, so I'd have them up and away from open windows. If they fly around a bit, they'll show some krinkles, but it wasn't that big of a deal.

A vote for Tapcon...they are awesome.

How about hanging solar shade/ screens from the ceiling? You should be able to cut it to fit, it will help with energy costs and you won't have to worry about jury-rigging curtain rods. I feel like there was a recent post on that solar fabric on AT lately. Just google, there are a lot of places that sell it by the roll.

don't know where you live, but i just ran across this ad on San Francisco Bay Area craigslist. even if not within striking distance, it is an interesting idea that you might be able to copy
http://sfbay.craigslist.org/nby/fuo/2442531224.html

RediShade temporary self adhesive shades! ;-)

If you can find a tension rod long enough, you could hang curtains at whichever height you want! We've used them all over the place to section things off (rooms, closets, I cut my office off in one section to create some storage). Oddly, I haven't used them in windows, but my parents both do in their individual spaces.

@kitkabbit: I agree 100% with using energy saving shades! You can get the fabric, and very easily sew them yourself!

I live in a concrete house. I ran gas pipe up from the floor. Works great. A few fittings right angles and a tee in the middle to prevent sag and your set.

I had a similar situation myself. Hospital track in the ceiling, using Tapcon screws as suggested if it's concrete. Use a drill with a cord as opposed to cordless to pre-drill, much easier. Then go down to fabric row, south of South Street. I forget where exactly, somewhere near 4th Ave Deli, been a long time since I have been in Philly. You can get fabric to do curtains that are the perfect size super cheap.

Lots and lots of tall, thick plants. Think of the oxygen output!

People gave you great ideas about how to hang your drapes, and the s hook idea is good and since it is industrial loft, why not use industrial wire (that silver wound stuff) to support the middle of the rod from the ceiling - line them up with the window casing instead of in the middle of a window. My windows span 22 feet across and I actually used copper plumbers pipe and connections (Home Depot) to connect my 2 pieces of pipe - heck of a lot cheaper than a curtain rod at that length. As for drilling into the aluminium, and then having a heating problem, why not add silicone to the hole before putting a plastic wall anchor in (and dab of paint same colour as the casing to hide the hook? Just a thought. I'd go full length curtains as well though. If you are worried about the cost for curtains that long, Ikea curtains are really long - then buy one extra pair in a contrasting colour and cut and sew to the bottom/top of the other panel to get a full length panel.

I have the same size windows in my loft and wooden blinds look great with the brick and work great too.

http://www.hunterdouglas.com/our-products.jsp?so=ft&sop=hp#/P_32/

I like the idea of hanging a track from the ceiling and having full length drapes. For something to give privacy and let in light, I would hang ceiling to floor arctic (white only) camo net. Cheap, and gives a soft almost lacy effect, but with a bit of an edge to suit the industrial space.

Do you have anything against top down bottom up shades? They install from the ceiling and offer a lot of flexibility.

I don't understand why you can't drill into concrete/cement walls? Those are the only kind of houses around here and we hang curtain rods all the time. Is it maybe something about building codes in the US that I don't know about?