You would need a tight sealed door to the structure for efficiency reasons. So because of that a barn door would be least efficient.
If the door doesn't seal tight when closed, you will lose heating and cooling thru the openings of the door.
If you want a sliding door you could use a patio style all glass door.
The more glass you have the least efficient it is, but if it is out of the way of the sun via sunlight infiltration it should be ok for most uses.
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Good note on back splash. With all white we can mix it up a bit with the texture in backsplash .
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