Can you use "CLO" ratings to get you in the ball park? And what "type" Primaloft is it?
Ayce from Thru-Hiker says:
In a well sealed bag with good ground insulation
clo 2 @ 40 deg
clo 4 @ 20 deg
clo 6 @ 0 deg
There are a lot of variables in play that can have a big impact on that chart: use it without blinders.
Quilts have trouble below freezing. Make sure you design in a good way to seal it up.
Also from his site: http://thru-hiker.com/materials/insulation.php
I see he has Primaloft Sport with a CLO rating of .79 per oz.
So, with Sport anyway, 7 oz/sq.yd X .79 CLO per oz= CLO 5.53
Which as you can see results in a rating WAY warmer than what is being suggested by other users experiences. And some one like Wiggy would ridicule the concept of CLO.
However, using CLO to guestimate warmth with Climashield does seem to give pretty accurate results for several folks at HF. For example, using 1 layer 2.5 oz CS in the WB UQ, with a CLO of 2.05 ( I think it was CLO .82/oz) kept me warm in mid 40s with nothing but cotton t-shirt and jeans, though I did feel I was at the limit. While I (and family members) have used it with more layers at colder temps, none that could test the CLO ratings because we did not approach the theoretical limits. However, Cannibal did take his, with a CLO of ~ 8, to minus 11F with plenty of base layers. See post #3:
I suspect we might need a little more CLO ( or loft with down) for UQ ratings than TQ. But if things work the same with PL as CS, find out what the CLO rating is for a ball park guess.