Micro optimisations

Micro optimisations are pointlessly¹ small optimisations that don’t really make enough of a difference to matter, but are fun to do anyway.

I like them and probably do them a bit too much. Here’s one that brings zero pain or inconvenience to your life, but just might save the world².

Use your dishwasher’s delay function overnight and cut your home’s electricity-based carbon footprint by 6%!

Here is it in super short form.

• On average I use ~44kWh per week of electricity at home

• My dishwasher apparently uses ~1kWh per cycle

• I run the dishwasher ~6x per week

• :. my dishwasher accounts for ~13.5% of my home’s total electricity consumption (!)

• I typically load the dishwasher somewhere between finishing dinner and going to bed. It takes a few hours to run, so is guaranteed to finish while I’m asleep.

  • This means I don’t actually care WHEN it runs, as long as it’s finished by the time I wake up

• My dishwasher has a delay function (3h/6h/9h).

• The carbon intensity of electricity typically peaks between 6-9pm, and typically bottoms out between 12:30-3:30am

  • The peak-to-trough drop is ~50% (wholly unscientific eyeballing of some 1-month carbon-intensity charts)

• :. I can set my dishwasher to delay its start and halve its carbon intensity.

• With some terrible assumptions, approximations, and “maths” and that should go absolutely nowhere near any real or professional problem³, I can argue that halving the carbon intensity of 13.5% of my home’s electricity lowers my home’s overall electricity-based carbon footprint by ~6%

Slightly longer form, where I actually query the official carbon intensity API

Maybe I’ll do this after the New Year period.