How far back in time could we travel and still more or less maintain our current (western) living standards? How far do we have to go back until houses reflect modern day standards, regarding everything from electrical lights to indoor plumbing?
The post-war period is really when this happened. Think, late 1940s to the early 1950s. Electric utility companies, home builders, and appliance makers put on a concerted effort to build home power consumption by making electricity consuming appliances like refrigerators, air conditioners, ranges, etc into a 'necessity.' It was a great business move for everyone, as people felt like they needed new homes and appliances and all of these interests got to increase consumption.
Source: Andrew Needham. Power Lines: Phoenix and The Making of the Modern Southwest