Since
people spend about a third of the day awake in their home, let us assume that a third
of their electrical needs are to be supplied in their home, or 2000 kWh/person/year.
Dividing this by 365 days in a year gives about 5 kWh/person/day, or 20 kWh/day
per family of four. This is consistent with household data from various sources for
the US and Europe