how can I calculate efficiency of electricity in my home?

Answer 1

Turn off every electrical appliance in your home. Unplug everything electrical until your electrical meter stops. Get an accurate reading of your meter. Go in and turn on an appliance of known wattage, like a 1000 watt hair drier. Leave it on for, say, 6 minutes. It should consume 0.1 kilowatt hours. Go out and read the meter again. Subtract your first reading from your second. The difference is what your meter registered in kilowatt hours. Try this at different outlets. Unwanted resistance will give you a measurement lower than expected. Unwanted resistance will also create heat where it doesn't belong, and could start a fire.
Check for lamp wires running underneath rugs. Multistrand copper cords degrade over time. That's a fire waiting to happen.
Also, if you live in an older apartment, your neighbor could have part of a circuit on your meter. If you turn off everything in your apartment and your meter is still spinning, this could be the cause.