To read and register power, gas and the temperature sensors I use a couple of arduino boards.
I had totally no experience with arduino or resistors / sensors so it was a good bit of trial and error to get things working. But with Dr Google and other users you get it working fine!
It did take me some time to find a good overview of the minimal parts etc that I needed to get started, and a few issues which I ran into. I will there include an overview of the parts that I needed to get going.
I have 3 arduino boards, 1 Arduino Ethernet (for power meter) and 2 Arduino Uno with 1 Ethernet shield for gas and temperature sensors. And a spare one to test configurations / play with (without ethernet shield). I purchased 2 of them at dutch retailers, and the last one using ebay for about eur 12.
I measure our power meter with an analog light meter to sense the LED flash per 1kW. To get the gas meter connected I use an IR sensor, but this was really trial and error as our gas meter doesn’t have any form of magnetic field and also no mirror on any of the digits.
To save the data and get some graphs I decided to not use my homeserver etc. I have a server running here, but I put this in standby at night, so I decided to use the database which is available as part of the website hosting. This is running PHP and MYSQL which is more then enough to serve my needs. Additionally I do not have to worry about backing up my data or troubleshooting if thing go wrong.