I'm confused about what you're asking! Are you looking for something that does fine in temps that go down to 30F upon occasion? Because I don't consider that particularly hardy.

I'm pretty sure that's what you're looking for. Some of the most commonly grown woody, evergreen vines for the south are Confederate Jasmine (Trachelospermum jasminoides), Asiatic Jasmine (Trachelospermum asiaticum), Carolina Jessamine (Gelsemium sempervirens), Swamp Jessamine (Gelsemium rankinii), and Armand's clematis (Clematis armandii). Those are just the plants that I'm very familiar with....I hope that others will make some suggestion, too.

These would be solidly hardy at 30F, even in a container. If you'd like further cultural information about any of these, just let me know. They are each quite different from each other, though all quite well known for their flowers.

Are you asking for your own location? I, too, live in a zone 7 location, but we experience temps into the teens every winter. I guess that's why I'm a little confused. :-)

rhizo,
Thank you for answering.
I have unheated sunroom (first year) where i wanted to create some kind of garden. In summer there was very hot on sunny days, but now night temp only couple degrees lower than outside. I live north of Seattle, some consider it's zone 8, but from my experience in my backyard i have zone 7. Here might be days when temp lower than 30F in winter, but i am planning to put some heat in sunroom when such cold is expecting.
So i am looking for plants (evergreen) to grow in containers and just jumping from one idea to another (conifers? vines? something else?) Something tall, green, not sure about flowers. Should stand high temp in summer and low in winter, western sun. I was thinking about cofee, tea and lemon trees originality, but looks like in winter they will be cold there and i prefer not to heat sunroom all the time. It gets warm there on sunny days even on cold days.
Currently i have there only couple small lemon trees on a side close to house. I covered them with row cover on cold nights.
I will look into vines that you have suggested and will appreciate any other ideas.
My garden experience mostly in veggie and flower gardening outside, not a lot of container experience at all, though i like this forum and often come here.

thanks
Gail