yes! my torts use a vivarium and they absolutely love it
they have access to this, a coldframe, a greenhouse (new this year) and a wooden house but the viv is where they prefer to be
here it is

I have been using coldframes for at least ten years, and find they work brilliantly too!!
Its surprising how much heat they hold.

I was expecting to see a pic of your viv???

Nice cold frame, where did you get it??

Until I had my greenhouse, mine had a coldframe and used it all the time
They are great little things

it's not a coldframe - it's a glass viv it's been in the garden for few years now, not rusted in the slightest
it's turned upside down and one of the glass doors is permanently half open but there's a tunnel the torts use to get in and out of
they rarely use their coldframe but i'm hoping they're gonna love their new greenhouse

i think its great you would know it was a viv

Great idea!