Tempshifts are merely 3x3 buildings. Tempshifts have 160kg effective thermal mass, compared to a normal tile's 200kg. This is because buildings count for 1/5th their mass. They have normal building interactions when buried in solid (200x heat transfer) or submerged in fluid (1x heat transfer). When utilizing them for thermal capacity, it is best to cover as much area as possible. It is. You can heat up neutronium with tempshifts, but not cool them.