The affix kan comes in the sense of 'who goes to work thus' after the words śīta and uṣṇa,
The word शीत and उष्ण being used as adverbs will be in accusative construction. As शीतं करोति 'who goes to work coldly' i.e. a lazy man = शीतकः = अलसः, जडः. Similarly उष्णकः = शीघ्रकारी, दक्षः 'who goes to work hotly'.,