5 ms·

Is there evidence for a real correlation beyond the obvious spurious one: Newer bulbs are more efficient and at the same time have a shorter lifespan due to pla

Is there evidence for a real correlation beyond the obvious spurious one: Newer bulbs are more efficient and at the same time have a shorter lifespan due to planned obsolescence.

formerly_proven 3y ago
No, this has never been researched.
rcxdude 3y ago
The arguments from the basic physics of the problem makes sense: hotter bulbs means more light relative to heat output, but also shorter lifetime. It seems quite hard to get out from under that tradeoff even with improvements in the underlying tech (materials, manufacturing, etc).
- trompetenaccoun 3y ago
  More efficient bulbs would be less hot, not more. The more energy gets converted to visible light instead of heat radiation, the more efficient the bulb is. So this argument only makes it more questionable, according to what you're saying modern bulbs should be lasting even longer than those old ones.
  - rcxdude 3y ago
    Not if you're using incandescence (LEDs and fluorescence use different mechanisms where this tradeoff doesn't exist in the same way). Incandescence is black-body radiation and the thing about black-body radiation is that as the temperature increases both the total energy given off and the proportion of higher energy radiation (useful visible light) to lower energy radiation (waste infrared) increase. So a hotter incandescent lightblub is more efficient than a cooler one (at least up until the point that it's so hot it starts giving off too much ultraviolet light, but that corresponds to a temperature at which no material is solid), though still pretty shockingly inefficient. Note that heat output and temperature can change seperately: a bulb running at a higher temperature (what I mean by hotter) can either have more light output for the same heat output, or less heat output for the same light output (for example, if the filament is shorter).
  - retrac 3y ago
    The hotter an incandescent element is, the more efficiently it converts heat to light. Think about how something metal and hot glows dull red, while something metal and really hot glows orange-white. Reaching white-hot is a trade-off, in balance with the limit of the material for how hot you can run the filament, before it boils away.

Is there evidence for a real correlation beyond the obvious spurious one: Newer bulbs are more efficient and at the same time have a shorter lifespan due to planned obsolescence.

formerly_proven 3y ago

No, this has never been researched.

rcxdude 3y ago

The arguments from the basic physics of the problem makes sense: hotter bulbs means more light relative to heat output, but also shorter lifetime. It seems quite hard to get out from under that tradeoff even with improvements in the underlying tech (materials, manufacturing, etc).

trompetenaccoun 3y ago
More efficient bulbs would be less hot, not more. The more energy gets converted to visible light instead of heat radiation, the more efficient the bulb is. So this argument only makes it more questionable, according to what you're saying modern bulbs should be lasting even longer than those old ones.
- rcxdude 3y ago
  Not if you're using incandescence (LEDs and fluorescence use different mechanisms where this tradeoff doesn't exist in the same way). Incandescence is black-body radiation and the thing about black-body radiation is that as the temperature increases both the total energy given off and the proportion of higher energy radiation (useful visible light) to lower energy radiation (waste infrared) increase. So a hotter incandescent lightblub is more efficient than a cooler one (at least up until the point that it's so hot it starts giving off too much ultraviolet light, but that corresponds to a temperature at which no material is solid), though still pretty shockingly inefficient. Note that heat output and temperature can change seperately: a bulb running at a higher temperature (what I mean by hotter) can either have more light output for the same heat output, or less heat output for the same light output (for example, if the filament is shorter).
- retrac 3y ago
  The hotter an incandescent element is, the more efficiently it converts heat to light. Think about how something metal and hot glows dull red, while something metal and really hot glows orange-white. Reaching white-hot is a trade-off, in balance with the limit of the material for how hot you can run the filament, before it boils away.