As the subject states, I recently bottled a winter warmer and even after 3 weeks of conditioning at around 66-70F it still has no to very little carbonation, which makes the malty, 8% ABV beer a little nasty to palate. This is my 12th brew so I have a solid knowledge of how much priming sugar (dextrose) to use. I used 3.9 oz of dextrose in 2/3 cup water, also mixed well in the bottling vessel. Just before this winter warmer I brewed a DIPA that I carbed with the same amount of priming sugar and it turned out perfect. All other environmental factors are the same, conditioning temperature and final beer volume. Also, on the NB Priming Sugar calculator using the ambient temp the recommended amount of bottling sugar is 3.9 oz, which I straight up guessed and came out being perfect for 2.2 CO2 volume.
My DIPA was FG 1.010, dextrose bottling addition of 3.9g to about 5.5 gallons and conditioned at the same 66-70F. The DIPA yeast was WLP-001 but was not cold crashed to the same extent, the DIPA was cold crashed in my sink by surrounding the fermenter with ice which did cool it down a tiny bit but not for long enough time to make it super effective. The winter warmer was cold crashed in my cold, Colorado garage for half a day and dropped the batch to about 50F. I highly doubt this was enough to kill/put the yeast into a dormant state. The winter warmer FG was 1.018, 8% ABV, using WLP023 Burton Ale yeast. Both were brewed using a 1L healthy yeast starter. I have remaining 46 bottles still conditioning in my "warm" kitchen at 66-70F. Is that not warm enough?