TL;DR Rethink lighting. It isn't "bulbs" any more, it is an appliance.
The key is expected lifetime.
Do you know how long a major appliance, one that costs hundreds to thousands of dollars and, if it has a gas connection (gas water heater or furnace or cooktop or oven) or real refrigerant work involved (AC except for mini-splits) or other work (e.g., built-in dishwasher, oven, etc.) requires a lot of work to install will typically last? 10 to 15 years.
Yes, there are outliers. If your furnace lasts 30 years with occasional maintenance, that's fantastic. If your water heater lasts 20 years before it rusts out, great. Personally, I try to stretch my appliances to 20 - 25 years, and sometimes it works (but the dishwashers are definitely showing their age) and sometimes it doesn't (water heater most recently). But these things, which are expensive and require a lot of work to install often don't last all that long.
Historically, lighting has been different. A chandelier or other light fixture using Edison bulbs would typically be installed once and expected to last "forever" because it is essentially a passive device. But the bulbs themselves? 1,000 hours is typical, and has been for a century. Unless a fixture has something else in it (e.g., motion sensor or dusk/dawn sensor, both of which can also be separate items rather than integrated), the more common reason to replace a fixture is "style". I don't care much for that myself, but replacing light fixtures after 10 - 20 years because you are remodeling is not at all unusual.
Fluorescent lighting changed things a bit. A typical fluorescent fixture (not talking about CFLs) has:
- A box with wires (i.e., similar to an incandescent fixture)
- A ballast
- A starter
and holds special bulbs, typically 2', 4' or 8' tubes.
Fluorescent fixtures have been fairly well standardized for decades. Standard bulbs that are replaceable like Edison bulbs. Standard starters that are replaceable like Edison bulbs. Mostly standard ballasts that require taking apart the fixture to replace them. So replacing a typical fluorescent ballast is half-way between "replace a bulb" and "replace a fixture". That being said, until good-quality LED lighting came along, it made sense to replace the ballasts when they failed because the rest of the fixture was passive (like incandescents) or easily replaceable items (like incandescents). A typical fluorescent bulb might last 10,000 - 15,000 hours - 10x an incandescent bulb. A typical ballast might last 10 - 15 years, longer with low usage.
To be honest, once you are in the 10 - 15 years range, you are now up to "replacing things isn't so bad" range. Because it is just like a major appliance.
When does it pay to replace a major appliance?
- When some new feature comes out that just gotta have (ice maker in the refrigerator? convection mode in the oven?)
- When the new appliance is a lot more efficient (HVAC)
- When the cost to repair is a significant portion of the new cost (almost any appliance at some point)
So back to lighting. LEDs have come a long way. What started to make them popular was ease of replacement (Edison bulbs) and lower pricing (often including utility or government subsidies). But the big savings really come from longer lifetime and lower energy use. Incandescent 1,000 hours. Fluorescent 10,000 hours. LED? 50,000 hours, 100,000 hours or more! And that's not even until "dead", that is typically L70 - 70% of the original brightness.
Once you get to these types of lifetimes, a light fixture becomes less like a traditional light fixture and much more like an appliance. It is quite likely that a good quality LED fixture installed today will last so long that you will replace it before it has reached "L70", simply because you want a different fixture - whether for cosmetic/aesthetic reasons or to provide more functional lighting for a new use of an existing room.
Looking back at the appliance example
- When some new feature comes out that just gotta have
Hard to say what that might be. Most features (dimming, timing, remote control) are easier done from the switch than the fixture. But 10 years from now, who knows!
- When the new appliance is a lot more efficient
Not likely with LEDs. See this Wikipedia page for some details but basically incandescent bulbs are in the 1% - 3% efficiency range, fluorescent 10% - 15%, and LEDs are already up to around 30% (not all of them are, but some of them are) and for "physics reasons" we can't actually get to 100%. I expect there will be incremental improvements for years to come (the LEDs themselves won't change so much, but the driver circuits likely will improve quite a bit), but there won't be a dramatic change as there was from incandescent -> fluorescent -> LED.
- When the cost to repair is a significant portion of the new cost (almost any appliance at some point)
This is still the biggie. For mass production, patent and other reasons, typical LED fixtures are (a) not usually designed with easy-to-replace driver circuits (this would be the equivalent of replacing a ballast) and (b) typically have relatively proprietary components (compared to the decades of very much standardized fluorescent fixture components). But if that replacement isn't every year but rather ~ 10 years, or even longer, it just doesn't matter. You replace it with the latest and greatest available at that time.
I have a pair of fixtures in one room. They were originally 2-bulb incandescent fixtures that didn't produce enough light. I replaced them ~ 1997 with fluorescent 2' 2-bulb fixtures. Only slightly less ugly, but produced a lot more light. Last year I replaced them with some Costco (not Costco brand but essentially "made for Costco") integrated LED fixtures. Much brighter (I installed a dimmer to take care of the expected family complaints of "too bright"), very low profile (which looks a lot better than either of the previous fixtures) and uses less power. Will they last 10 years? I hope so. But if they last 5 years I'll be perfectly happy. Installation isn't that hard, and the integrated fixtures provide a low profile that is impossible to get otherwise - at least not without cutting a big hole in the ceiling.
