The local orange box store is now carrying the 10.5 W Cree CR6 (R30 replacement) for ~$30 (well under internet pricing from numerous vendors), so it seemed worth risking $60 for a pair of sockets where dimmable edison-base CFLs weren't delivering acceptable performance on the low-luminosity-end.

Right out of the box:

The color temp of the two units differed noticeably, but not enough to bring me back to the store.

On the original 1980s vintage Lutron dimmer they flickered horribly at the bright end of the range, but at half luminosity and lower they were fine.  Replacing the antique dimmer with a more recent low-end Lutron (model TG-600PR) it's still possible to find a few narrow settings where the CR6s will flicker, but for most of the range they dim acceptably & stably (but not as smooth & nice as a pin-base CFL in a dimmable fixture). 

At very low luminosity it's possible to see blue & red fringing on the LED through the diffuser, but it's not objectionable.  The color temp difference between the pair is more noticeable at the very low end of the range, but still not too objectionable.

The heat-sinking & ventilation design is dramatically less than the (more expensive) Cree LR6 but the max-luminosity is a bit less too (575 lumens as opposed to 650 lumnens on the LR6), but they're otherwise quite similar, with comparable ~55 lumens per watt efficiency (better than most cold cathode bulbs, but lower than pin-base CFLs in ballasted fixtures.)

Visual efficacy is quite good, with good color rendering (better than all but the very best CFLs) and low glare.  In non high-ceiling applications where you don't need the high-end lumens they're decent- better than many "cone of light" high-glare lower CRI R30/PAR38 LED units out there and anywhere near that price point.

The CR6 fills the bill for my intended use, and since they'll be run mostly at 1/2 to 2/3 power they should outlive their 35000 rated hours even without the bigger heat sink of it's LR6 sister.  At the $30 price point it's a decent value, but I'll wait for the L-prize PAR38 entries to show up before swapping out the edison-base CFLs from other R30 sockets, which will have 2x the efficiency and 2x the high-end luminosity.

Lifetime $ per lumen/hour is the metric I am interested in. Of course it varies widely depending on hours/year (don't use an expensive LED bulb in your closet).

Since the initial price point of the L-prize PAR38 is also $30, and the min-lifetime is 25K hours, the CR6 is about twice as expensive as an L-prize winner in lifetime $ per lumen/hour terms. The initial price is dwarfed by the operating cost numbers when you're talking lifetimes that long- it's all about the luminous efficiency. Min-spec on the L-prize is 123lm/w for the PAR 38, which is a bit more than 2x that of the CR6/ LR6.

The initial price could be dwarfed by the operating cost - but only if you use it for sufficient hours/year.

where are you buying for $30?

Posted By jonr on 16 May 2011 04:30 PM
The initial price could be dwarfed by the operating cost - but only if you use it for sufficient hours/year.

Somehow I perceived your financial analysis to be relative to total cost over the product lifecycle.  Mind you at 35000 hours you may move on (to another house, or the great beyond) before they burn out if you're not actually running them many hours.  At only one hour a day that 35000 hour LED is going to last ~95 years, and an 8000 hour CFL would last ~22 years (probably a bit less, since every on/off cycle incurs a fixed incremental degradation that's greater than a few hours of continuous operation, and the 8K hour estimates are based on 3 hours of use at a time. But still it's a long, long time.)

But most lighting fixture run more than 1 hour per day, many more than 10 hours. A lifecycle estimate isn't ridiculous, particularly for high duty cycle use.  At $0.15/kwh a $5  R30 15W CFL uses $18 in power (total of $23) to run over it's full 8000 hour lifespan, and in that same 8000 hours a 10.5W unit that cost $30 has burned only $12.60 in power (a total of $42.60) but it is less than 1/4 of the way into it's operational life. 

If you keep swapping in the $5/8000 hour CFLs, the fifth one would be nearly half-toasted by the time the first LED unit quits, so you would have spent $25 on CFLs + $78.75 in power ($103.75 total) to run with CFLs, vs. $30 for the LED + $55.13 in power ($85.13 total) with the LED.

Whether the LED costs $5 or $30 is probably "in the noise" of the actual electricity pricing over the very long lifecycle of the unit.  But doubling the efficiency makes a real difference in lifecycle cost.  If you have to PAY somebody to swap out bulbs (as in many commercial applications), labor cost alone tips the balance well in favor of LEDs.

For me the decision to buy this pair of LEDs was the better dimming factor.  I'll probably never replace them, since they're rarely run at full power (extending lifetime by lowering the operating temp) and not a huge number of hours/day.  When better (==2x efficiency) R30/PAR38 LEDs are availble at anything like that price,  some of the R30 CFLs in other sockets in my house will get recycled as they near end-of-life (but not before then) since the dimming isn't as critical, and the light output requirements at full-power is higher than the pair I swapped out for LEDs. YMMV.

Yes - and the majority of bulbs in my house operate less than 1 hour/day. So for most of them, replacing them with a $30 bulb will never ever pay for itself even if it used no energy and lasted forever. It's the cost of money.....

Posted By jonr on 19 May 2011 12:45 AM
Yes - and the majority of bulbs in my house operate less than 1 hour/day. So for most of them, replacing them with a $30 bulb will never ever pay for itself even if it used no energy and lasted forever. It's the cost of money.....

Then the relevant "lifetime" is YOUR lifetime, not  lifetime of the LED or CFL in your statement:

"Lifetime $ per lumen/hour is the metric I am interested in."

Any of the above would outlast you at your duty cycle.

No, the statement is also true if I lived forever. The savings just isn't enough to offset the up-front cost - ever. Present value < $30, even for a perpetual "income" stream.

Depends on your presumed discount & energy- inflation rates, and the actual duty cycle you're running it. But you can spend a lot more of your valuable time doing the full NPV calc to optimize what to stuff in any individual socket than it's worth.

You all are forgetting on thing for home use ... resessed lighting fixtures require to vent to an open space (in most cases an attic space) in winter cold air pours down into the room from the attic spaces thru the fixture ... the CR6 with its frame and rim seals off the room and stops the loss of heat and eliminates the draft. I have 14 lights in a great room, hall and kit ... all vent into attics, I am in Virginia ... for me its like having a window about half open ... not sure how to add that savings in but when I get 14 of these lights, I know my break even point will be in less than 8 years not decades. Image what it would be in New England ... 5 years or less. I think the insulating factor; since the LED lets off no heat, is far greater than the electric savings. But hey what do I know, I am just a simple home owner.

Posted By amazgj on 04 Sep 2011 09:00 AM
You all are forgetting on thing for home use ... resessed lighting fixtures require to vent to an open space (in most cases an attic space) in winter cold air pours down into the room from the attic spaces thru the fixture ... the CR6 with its frame and rim seals off the room and stops the loss of heat and eliminates the draft. I have 14 lights in a great room, hall and kit ... all vent into attics, I am in Virginia ... for me its like having a window about half open ... not sure how to add that savings in but when I get 14 of these lights, I know my break even point will be in less than 8 years not decades. Image what it would be in New England ... 5 years or less. I think the insulating factor; since the LED lets off no heat, is far greater than the electric savings. But hey what do I know, I am just a simple home owner.

Do you have a link to the lights you are referring to -  The ones that will replace the recessed lights?

Posted By amazgj on 04 Sep 2011 09:00 AM
You all are forgetting on thing for home use ... resessed lighting fixtures require to vent to an open space (in most cases an attic space) in winter cold air pours down into the room from the attic spaces thru the fixture ... the CR6 with its frame and rim seals off the room and stops the loss of heat and eliminates the draft. I have 14 lights in a great room, hall and kit ... all vent into attics, I am in Virginia ... for me its like having a window about half open ... not sure how to add that savings in but when I get 14 of these lights, I know my break even point will be in less than 8 years not decades. Image what it would be in New England ... 5 years or less. I think the insulating factor; since the LED lets off no heat, is far greater than the electric savings. But hey what do I know, I am just a simple home owner.

Not so!   In fact vented recessed fixtures in attics are specifically BANNED in some areas (including the entire state of Washington) due to their myriad heat loss & moisture migration issues.

Cold winter air doesn't pour down from the attic, rather, vented fixtures become a path for stack effect forces to draw humid interior air up into the attic to condense or freeze on roof decks & rafters, etc, creating  mold & rot issues.  Cold air is then sucked into the now-depressurized house in winter through all of the other air leaks.

LEDs certainly DO give off heat, just far less heat than an incandescents for the equivalent amount of light, or about the same amount of heat as compact fluorescents.  This is important in a ventilated fixture since the amount of localized heat in the fixture increases the localized stack effect and infiltration losses in proportion to the temperature differences created by that local heat.  A 100W bulb in a leaky fixture drives more than 5x the infiltration while on than when the bulb is off.  An 11W LED would create less than a 2x increase in most homes. But WA-code compliant gasketed air tight insulation-contact fixtures pretty much takes care of it no matter what type of bulb is the fixture, or whether it's on or off. 

It's code-legal to seal vented fixtures from above by boxing over them if you provide sufficient clearance, but it's often cheaper/easier to just swap the fixture. An air-tight gasketed fixture is a LOT less money than a CR6, last time I checked ($8-12 fixtures vs. a $30-50  bulbs.)  And the CR6 is NOT gasketed- you'd have to caulk it to the ceiling to achieve anything remotely like air-tightness.