Shelly sells a smarthome sensor called Door/Window2. It works well, use wifi, is very configurable and can be used locally, without cloud. Unfortunately they’ve chosen a weird, expensive battery option, CR123A. It can cost around 70 NOK (~10 USD), and does not exist as a rechargable option. And you need two of them! So what do you do if you only have one left?
Use a single, abundant 18650 instead!
In Norway electricity is the most popular form of heating for households at 96% (source). Pure 230V AC is a very high-level energy, and we don’t really need that precision for heating.
This is a project to see if easy, not-perfect, locally generated energy can be used to lower the heating bill.
Disclamer: this is mostly for fun. A more economic aproach would be insulation, heat pump, put on a sweater, etc.
“If you can’t measure it, you can’t improve it.”
Reducing energy usage is hard if you can’t see it. Here’s a cheap way to graph home or office energy usage.
By reading data from the energy meter, one can get super accurate, real-time usage data.
I’ve used:
You need some familiarity with all of the above to set this up.