I'm very energy conscious and have been so since a fairly young age, my late grandmother instilled that unneeded lights = wasted money = big sin. Therefore we always shut off the lights off when it wasn't needed. She was one of those that basically lived as if WW2 was still ongoing. Air conditioning in the summers were switched on only when there was a genuine need for it, otherwise the sea breeze will do, winter months, you can turn on the heat if you're still feeling cold after you've put on 3 layers and a house coat.
These days I work for a company that among other thing
s it sells is power-generation infrastructure and see the huge amounts of fuels required to keep a nation going therefore I tend to be rather conservative when it comes to usage of energy.
Lights, it depends on the type of light it is, if it is a CFL bulb or a fluorescent tube lamp then I only switch it off if I'm going to be out of the room for an hour or more otherwise it's better to leave it on as these lamps use as much energy as leaving the lights on for 2 hours just to start it up depending on the ballast and frequent switching it on and off will shorten the lifespan of the bulb.
Whenever I buy a new home, the first thing I do is I ensure the house is energy and space efficient. I never live in a place that is bigger than I need. After that I always ensure the building has most if not all the modern energy saving features installed if it isn't already installed.
Just recently I refurbished an old apartment, first thing done was to insulate it especially at the ceiling. Then I had all the windows replaced with triple-glazed ones for insulation, noise control and security, had a new boiler and under-floor heating installed, all lights were replaced with LEDs and controlled automatically to either dim or shut off by occupancy sensors. Also had several solar panels installed as these are "free" sources of energy. Appliances that are older were also replaced with newer ones that are more energy efficient and durable.
Hoping that would cut down energy bills and consumption by at least 2/3.