I assume MS has records of how many licenses they've sold (not much they can do about pirated software). They could come up with an estimate of how long a parti

I assume MS has records of how many licenses they've sold (not much they can do about pirated software). They could come up with an estimate of how long a particular OS was probably used on average and calculate how man licenses were sold times how long they were used and then convert that amount of energy use into carbon credits. It's not perfect, but probably good enough.