To reduce the carbon emissions of your whitegoods, simply time those devices to run when renewable generation is at its highest, being:
- at or around 1pm on a weekend, or
- at or around 1pm on a weekday, and failing that
- between 10am and 3pm on any day.
It's very easy to change the time that you operate whitegoods, as most modern dishwashers and washing machines have delay timers that allow you to delay the start (or finish) time of your wash cycle, and some clothes dryers have this also.
In South Australia the best time to run appliances is at or around 1pm. This is because, as an annual average, that is when renewable generation (i.e. wind and solar) peaks relative to all other times of the day.
It's even better to run an appliance at ~1pm on a weekend, because electricity network demand tends to be lower over the weekend and some renewable generators may actually be curtailed for lack of need. So where convenient, try shifting your usage to that period to assist more renewable energy in being fed into the grid.
Failing that, simply aim to run those devices between 10am and 3pm, as the grid's renewable mix will still be much cleaner then, when compared to most other times.