Question

what do you mean by retrofitting​

Answer 1

Answer:

add (a component or accessory) to something that did not have it when manufactured.

"motorists who retrofit catalysts to older cars"

provide (something) with a component or accessory not fitted during manufacture.

"buses have been retrofitted with easy-access features"

Answer 2

Answer:

to modify equipment (in airplanes, automobiles, a factory, etc.) that is already in service using parts developed or made available after the time of original manufacture. to install, fit, or adapt (a device or system) for use with something older: to retrofit solar heating to a poorly insulated house.