Say electricity costs 8.2 cents/kWh (a worst-case scenario, in terms of how worthwhile LEDs are). Say an LED lightbulb costs $3.25 (again, a worst case: I'm using the full price even though they're on sale right now), while an incandescent costs...okay, apparently the reason I can only find weirdly-shaped niche incandescents in the store catalogue is because Canada banned the normal ones in 2015, and presumably I did not really notice because why would I buy incandescents in the Year of Our Lord 2015 anyway. Fuck it, let's say they're free: LEDs would *still* be worth it under that assumption.
An incandescent ~800-lumen bulb would require 60 watts. An LED 800-lumen bulb requires 8.5 watts. The savings is 51.5 watts, which can also be expressed as 0.0515 kilowatts, which in turn can be expressed as 0.0515 kWh/hour.
[0.0515 kWh/hour * 8.2 cents/kwH] = a savings of 0.4223 cents/hour. We need to save 325 cents' worth of electricity, which takes [325 cents / 0.4223 cents/hour] = ~770 hours of run-time. That's about 64 days at 12 hours/day, 128 days at 6 hours/day, 193 days at 4 hours/day.
That's *before* getting into the longer life expectancy of LEDs.
no subject
Say electricity costs 8.2 cents/kWh (a worst-case scenario, in terms of how worthwhile LEDs are). Say an LED lightbulb costs $3.25 (again, a worst case: I'm using the full price even though they're on sale right now), while an incandescent costs...okay, apparently the reason I can only find weirdly-shaped niche incandescents in the store catalogue is because Canada banned the normal ones in 2015, and presumably I did not really notice because why would I buy incandescents in the Year of Our Lord 2015 anyway. Fuck it, let's say they're free: LEDs would *still* be worth it under that assumption.
An incandescent ~800-lumen bulb would require 60 watts. An LED 800-lumen bulb requires 8.5 watts. The savings is 51.5 watts, which can also be expressed as 0.0515 kilowatts, which in turn can be expressed as 0.0515 kWh/hour.
[0.0515 kWh/hour * 8.2 cents/kwH] = a savings of 0.4223 cents/hour. We need to save 325 cents' worth of electricity, which takes [325 cents / 0.4223 cents/hour] = ~770 hours of run-time. That's about 64 days at 12 hours/day, 128 days at 6 hours/day, 193 days at 4 hours/day.
That's *before* getting into the longer life expectancy of LEDs.