A smart home can be reliable, useful and environmentally friendly (if we consider potential energy savings). You just won't get there with consumer-grade solutions. Pretty much every consumer-grade tech nowadays is designed to generate "engagement" and collect data; the actual "useful" work it does is only the bare-minimum needed to convince you to buy the product and "engage" with it.

If you look beyond the consumer-grade trash, you can get somewhere nice with $500 if you go the DIY route with modules/relays supporting open protocols and Home Assistant, or if you have several thousands to spare check out higher-end solutions such as Crestron.

Any good system will be completely self-contained, not rely on the internet, and provided the hardware is maintained should last essentially forever.

Crestron may be as good as humanity can do for home automation, but it's the way to madness with proprietary development tools, security vulnerabilities, and hardware that still isn't up to infrastructure reliability levels.

> A smart home can be reliable, useful and environmentally friendly.

Unless you have free spare electricity, I think it’s very difficult for smart electric lighting to be environmentally friendly. The controllers simply need too much standby power.

For example, https://eprel.ec.europa.eu/screen/product/lightsources/84743... is a 5W IKEA lamp that uses 0,3W when powered off. So, the lamp itself uses 4,7W, and you can leave that light on for about 1½ hour every day for the power that the controller uses. Said otherwise, you currently have to have such a light on longer than needed for 1½ hour every day to make up for the energy use of the controller. Add in energy used to make the controller and it gets worse.

There are days where I accidentally leave on a light for 1½ hours, but that’s nowhere near the average over all my lamps over a year.

Smart lights give you convenience. They won’t help saving the environment.