epiphenomenal

Being of secondary consequence to a causal chain of processes, but playing no causal role in the process of interest.

An organism's consciousness is epiphenomenal to its behavior, and its behavior is determined by unconscious calculations.

To this day, critics of materialism regularly recite the tenacious canard that the model crudely counterposes ‘economic’ factors to ‘culture, ideology and mentality’ […] That for materialism, thought is epiphenomenal froth. This is bogus.

Of or pertaining to a mental process that occurs only as an incidental effect of electrical or chemical activity in the brain or nervous system.

If qualia are epiphenomenal in the standard philosophical sense, their occurrence can't explain the way things happen (in the material world) since, by definition, things would happen exactly the same without them.