Keeping a Single Australorp

[aart]

is it possible to keep her acclamated to the Ohio winter, while letting her sleep in the house, which is around 65 degrees? Is that similar to the temp she'd be if another hen were supplying the warmth?

I would say not a good idea.... and no, not the same.

Big thing is the temp differences, a bird acclimated to the cold will not be comfortable in a much warmer house...... @bobbi-j has a wonderful analogy about 'feather coats '.

Think about this - when you go outside in the winter, you can put on your winter gear. Coat, ski pants, boots, hat, mittens, scarf. You go outside with all that on, and for the most part you can be comfortable. But what about when you go back in? Try leaving it all on for a couple of hours in your heated home.

 

[driver]

I had a six year old hen survive alone last winter just fine (probably similar weather to yours). I moved her very small coop/run right up next to the south side of the house, so a lot of the wind was blocked, and she got a lot of sun during the day. Building a shelter on your porch will probably do the same thing.