Hello, I am designing a custom home that will start construction likely in May.  I'm new to all this so having to learn a lot, and my general approach is to choose energy-efficient options as much as possible as long as they make sense financially.

In reading about LED lighting, it seems to me this is a great way to save on electricity while still having quality lighting, but that perhaps the cost right now is too high to justify.  If electricity consumption weren't an issue, we would want to put recessed lighting all over the place, but given the high energy cost of halogen, I'm not sure this makes sense.

So my question is this.  If I go with recessed lighting, is there a "standard" in terms of the bulb such that upgrading to LED lighting (when it becomes more cost-effective) will be just a matter of changing bulbs, or will I need to get new recessed lighting fixtures if/when I decide to go LED?

The Cree LR6 fits into most 6" incandescent can fixtures, (fixtures desgined for Edison base R40 floods) and will dim down to ~25% with some standard cheap incandescent dimmers. They're under $100/pop even today, but only deliver ~55 lumens per watt.

But if you went with specular 4-pin-base CFL recessed fixtures with dimmable ballasts you can get higher efficiency (over 70 lumens per watt), better dimmability (down to 1-2%, but only with dimmers designed for those ballasts) and a broad range of inexpensive high CRI & selection of color temperature CFLs that fit those pin-sockets. For ambient lighting it's going to be the better choice for some time to come.

SFAIK there is no standards for LED specific fixtures in the pipeline, and they're so fundmentally different from incandescent or fluorescent technologies that it's a bit silly to expect that they should all work in the same fixtures equally well with a simple bulb-swap. Indeed, the reliablity of screw base incandescent-replacement CFLs is largely due to the fact that they have to pack the ballast electronics into the tiny base, which means taking design shortcuts on efficiency to save space, and higher temperatures that cooks the tiny ballasts into an early demise (particularly when in inverted operation.) You can expect the same from high-brightness LED technology incandescent lamp replacements when they hit mass-market penny-accounting manufacturing, sold by the 8-pack in box stores.

Hopefully an LED fixture standard will emerge, but it's not there yet.

mlennox
What type of fixtures are you planning on using now?
Most of the LED specific fixtures on the market now mimic sizes of current halogen, incandescent or florescent. And are expensive.
They are not necessarily the most efficient either.
Lastly, LEDs come in many shapes and sizes, so any repair would require the proper replacement.
You could not go to Home Depot and pick up a spare lamp.
If you are looking for direct replacement lamps for halogen fixtures you may have better luck.
Lamina makes a direct replacement for GU5.3 and GU10 bases.
It is not the most efficient lamp out there but it does have a good lifetime and a few colors of white to choose from. Cheaper than the Halogens you would be replacing over the life of the lamp.
Also no need to add fancy dimming ballasts or expensive dimming controls.
If you were going to install Halogens that use this lamp you should consider this option.
I would wait a year to change over to the LED lamps though. The Lamina's have been on the market about a year, the price is bound to come down and efficiency go up.

LEDs are semiconductors. They use the same elements as transistors.

LEDs are rated by current, not voltage. It does not matter what the voltage, as long as the current flow is proper.

Currently, the most efficient LEDs are the monochromatic ones (single wavelength/color). Unfortunately, the available LEDs are still MUCH less efficient than the worst fluorescent lamps.

The white LEDs use a phosphor coating to achieve a spread spectrum (more than a single color). These are even less efficient than the monochromatic LEDs.

The 4-diode configuration, which you mentioned is used to convert AC to DC, is called a "full-bridge rectifier". The output has a severe "ripple" in the shape, which is lessened/smoothed by the addition of a capacitor. That output is closer to 170 volts, not the 110 volt figure. 110 volts is the RMS (root-mean-squared) value of the AC.

There are a lot of variables involved on where and how you can use LED if that is what you'd like to do.  Undercabinet lighting is a place where LED can shine.  Kichler makes UC light that provides plenty of brightness and has great color rendering.  The LR6 that was earlier mentioned is GREAT as long as the ceilings are 9' or less.  They will definitely pay for themselves in the long run.
   For residential applications many builders and homeowners don't appreciate halogen as much as they should.  You get the best color rendering, a very bright light, and when you dim them the bulbs last exponentially longer.  They are also fairly energy efficient when you dim them as you only use the amount of light necessary for a given task or time of day.
I hope this answered some questions take a look at some of these lighting tips for more information or  contact me

Just remember if you go fer LED, no matter what you do get good quality fixtures. Cree made LED's are great and will hold up for teh expected life. I've had so many customers come in with problems because they bought something that looked like a great deal, but doesn't last a1/10 the time it was supposed to, or provides blue or green light.
Thats's my advise, if good quality LED can't fit in the budget just go halogen for now and upgrade lated.
http://www.villagelightinginc.com/lighting_tips.html

When you say "upgrade later", is there anything that should be considered when installing halogen that will make upgrading later much easier/cheaper?  Are there certain halogen fixtures that will accept a LED bulb more easily when I upgrade, or am I going to be replacing the entire recessed fixture anyway?

As far as recessed, which is what you seem most interested in, the LR6 will retrofit into any of the major recessed can manufacturers cans. I use Juno and the LR6 works perfectly with them. The LR6 simply pressure fits into the housing.
Also in regards to the earlier comment that LED is less efficient than flourescent? Where did you get that from? The LED I've seen, and pretty much all of them, kick out more light per watt than anything EVER? It is a different kind of light that is directional and not general. Flourescent is much better suited to general lighting, but it CAN NOt be a point source, therefore it will never be efficient at directional lighting.

Thanks for this.  Presumably though If I have halogens with dimmer, the dimmer function won't work properly when I upgrade to LR6?

The Cree LR6 works with a standard dimmer .  Just use a Juno IC22 with a baffled trim and a 75 watt PAR30 bulb.  Put that on a Lutron Dimmer and you're good to go.  You may not even want to change them out once you see the bright light halogen can provide, or you can do what I did, and just change out the kitchen since the lights ae always on there.  Visit my website at Village Lighting and if you'd like contact me directly.  I would be more than happy to help you with your layout, answer your questions, and provide your lighting.

You'll want to work with an experienced lighting salesperson or lighting consultant to amke sure the dimmer you get can handle a very small load well. That may be one thing that you'll need to replace when you retro fit LED

It's not hard to just read the specs & measure the output eh? (That's where I get that from!  ;-) )

As an electrical engineer I've designed LED illumination systems for eye surgery equipment & infra-red imaging apps as well as precision controlled fiber-optic gyros.  I daresay I know my lumens/watts/candelas better that most, and I surely know how to read the component spec on an LED, and the current controls that drive 'em.

The CREE LR6 is great (one of the best in the industry) but it still underperforms most current CFL R30 floods from a total luminance/watt point of view- not by huge margins, but easily measurable.  Be prepared for measurably lower operational luminance in higher-temp apps though
  
No argument about point-source/sharp shadows vs. ambient lighting though, and LEDs KILL low to medium power halogens on efficiency where

(I meant to finish it as...)

...where sharp shadow edges and conical output is desired.

I've been out on a long weekend so I'm sorry it took so long to reply.  I researched more into the Lumens per watt of flourescent and LED, and surprisingly the total outputs are much closer than I thought they would be.  From a lighting consultants point when I put a 12 watt led light up against a 13 watt flourescent there is no comparison.  LED just puts a much brighter and more noticeable spread of light out. 

Well, there's a good quantitative measurement for ya! I'm convinced! ;-)

Don't confuse center-spot intensity with overall luminosity, and DO measure the intensity at the cutoff edge before claiming that it's the same or amount of light for ambient lighting apps. You'll find that most LED assemblies have many dB of intensity delta between the visible dispersion edge & center spot, whereas fluorescent technologies are much more uniform. In reflector form-factor bulbs the edge of the spot with fluorescents are usually determined by the bulb optics and will vary greatly with design, whereas most LED assemblies rely solely on the component optics with dispersion angles and edge intensity determined at the component level. Rooms lit with a bunch of LED R20s in cans usually have discernable round pools of light on the floor detectable by the sharp edge cutoffs, whereas with CFL R20 floods that's rarely an issue.

The logarithmic sensitivity of your eye can make up for a lot though- designing for room illumination is not the same problem I have when designing illuminators for surgery equipment, where maintaining a minimum uniformity of intensity counts. If you like 'em, think they're more pleasant, great, but you'll have to show me the numbers to make the efficiency argument stick. (Don't lighting consultants own light meters anymore, even a crummy broad-field luxmeter or something?)

Cree can accomplish 130 lumens per watt. Do you have a flourescent that puts out more?

 flourescent lumens per watt and
led lumens per watt
any questions?

Back to where this thread began, I would also suggest to anyone planning energy efficient recessed lighting is, if you can't afford the good LED don't go with flourescent. The light output and color will be poor compared to halogen or good LED, and you can't dim them for any less money than you could dim an LED. Go with halogen before flourescent for recessed. I really only specify flourescent for closets, outdoor lighting, and some indirect lighting circumstances.

Nate, what would you spec in a kitchen, where normally there would be one giant fluorescent fixture (which floods the room in a flickering eerie grey light)?