A change in your usage pattern could be used to ID any number of private things that could then be used against you:

- When you’ve gone on vacation and your home is unattended.

- When you have an additional tenant, a long-term houseguest, have a new significant other or even have a baby.

- Whether or not you’re actually working when you’re working from home.

- Homes that use greater than X amount of electricity are at greater risk of Y and so your home owners/rental/car insurance premium goes up.

- People who play computer/video games late at night are at higher risk for health issues is your health insurance premium goes up.

And I bet there are other, much more subtle things they could figure out once given the opportunity to vacuum up your data: like estimate what temperature you set your AC to and determine whether or not someone in the house was awake at any given moment of any given day.

At my house, I have a meter that I get a feed from. So I look at the graphs. From the graphs, you can learn about what is happening in the house. You know when someone is showering, left home for work (arrived home), doing laundry, went to bed/got up, used the microwave and so on. Some of that you could determine by watching the house, but that requires constant surveillance. A smart meter provides all this data with no effort and at mass scale. If I can glean that level of information just by glancing at the graphs, I'm sure someone better equipped could determine even finer grain details of what is going on in the house.

I am disabled and I was considering growing my own medicine in the event of losing job or not having funds for filling my prescription any more - hopefully that will never happen, but knowing that I have a smart meter, that would add a lot of anxiety that I don't need.

Usage patterns at the substation level are important. They don't need household detail.