Lighting has a cost, superior to what we think, despite the fact that Kilowatt-hour is not so high.
In order to estimate your lighting cost for the next year let's start by considering the total lighting cost C, that is given by
C = Ce+Cs+Cm
where Cs stands for material cost (the investment), Ce stands for electricity cost and
Cm stands for maintenance cost.
In the following table the ratio between the total lighting cost C and its components in the case of traditional light and in the case of EDISON.
To determine Ce,Cs,Cm we need to know