Location and size of Oehlers sink

Hi,
I wonder if anyone can help inform me about the relevance of size and positioning of the cold sink?  I believe the sink is along the south wall and just wide enough for access in Mike's design.  Is this for any reason other than convenience (eg. air circulation, keeping sink in shade etc)?  I'd like to keep the perimeter for growing which would make the sink central, are there downsides?  Also, is bigger better for the diameter of the sink?

I've excavated about 80% of the pit for a small (8'x12') greenhouse so will soon need to decide where to keep digging for the sink.
Thanks

The area farthest southward/front will receive the least amount of sunlight, thus a perfect place for a cold sink...  especially if there is a slight downward slope towards it.  I believe Mike had stated something about keeping rabbits? within the cold sink area (for the ongoing CO2), but that just seems cruel and messed up to me.  I was thinking it would likely make a great area (inside the cold sink) to store onions, potatoes, etc.... or even some canned good jars, by making a pallet like raised walkway just above, made of small sections that could be removed to reach in for these as needed.

Thanks for replying.

The bit I don't get is I thought the point of the rabbits and sink was also to warm the cold air that sunk.  If that is the case and there is no intention to keep livestock then surely sun on the walls and floor of the cold sink would be beneficial as it's all part of the mass I'm trying to utilize?

I've only ever seen it stated as the animals placed there for the added CO2.  Hmmmm

For the full breakdown, purchase the Earth Sheletered Solar Greenhouse Book
http://undergroundhousing.com/greenhouse_book.html
here is a quick breakdown of rabbit benefits.

Needing less rabbit feed in the winter since they are partially
warmed by the greenhouse atmosphere itself and need metabolize
less to maintain body temperature....
Guaranteed comfort on even the hottest of days. And, of course, on those freezing
January nights
"does in underground shelters were
8% heavier afier 2 months in the experiment, they gave birth
to 39% more offspring and weaned 60% more than those in
cages ..
The carbon dioxide (CO,) benefits of animals, especially
"The air contains only about 300 parts per million of carbon
dioxide...at 220 parts per million
of CO, "a slow-down in plant growth is significantly noticeable"
while below 150 ppm "most plants stop growing."...
DeKome estimates his rabbits raised his greenhouse
CO, to 700 ppm to 800 ppm,

I've read the book, then just read it again!  I may have missed it but I can't find any explanation regarding the need to shade the cold-sink if livestock is not kept in there.  I get the benefits of doing so, it just isn't possible for me, here,now.

I have a feeling that the idea is that some part of an underground space is unavoidably going to be shaded, so putting the cold sink there lets all the sunnier parts of the space be used for growing.

If you can get the beds on the south side up into sunlight without shading the beds on the north side, I suppose that would work, and the cold sink could be located anywhere you can put it while not interfering with movement or bed support. I do think that cold air would be flowing down preferentially from the base of the south-facing glazed wall/roof on winter nights, so directly below that might put plants in the path of the coldest air.

Good point on the cold air flowing onto the bed.  I'm going to proceed with a central pit as it works for me.
Thanks