Over at the Oil Drum, they look at the relationship between energy usage and happiness.
As can be seen, there is little correlation at all between subjective well being and energy use. (The actual r2 is 14%). Of note is the United States uses 39 times the primary energy as the Phillipines yet the percentage of the population that is `very happy' is about equal. While there is a low r2, this does not mean there is not a relationship.Of course this is based on the World Values Survey data for happiness and looks at those that self report being "very happy". Take this for what it is worth, as the accuracy of happiness studies is still suspect (Mexico and Venezuela are the happiest places to be??).
What about something more objective?
Vaclav Smil, in his book "Energy at the Crossroads" did similar work on objective measures of wellbeing vs energy consumption. A pattern similar to the above `boomerang' curve is found on comparisons of female longevity, sufficient nutritional food, educational opportunities, freedom etc. The shape is also the same, but inverted, for infant mortality. In general, Smil concludes that a reasonable level of well being on objective measures is achievable between 50 and 70 GJ/per capita, with marginal increases up to 100 GJ per capita. As a comparison, North America is currently at 340 GJ per capita. Again, the large excess consumption is not improving objective wellness.Sounds like a book I need to check out. 750 gallons of gasoline is approximately 100 GJ of energy.
From the article it appears that it is possible for the US to cut its energy use by 2/3 and still maintain its subjective and objective levels of well-being.