Low energy spots-any recommendations ?

On Sun, 10 Feb 2008 11:24:58 -0000 someone who may be "Neil" wrote this:-

Glad to hear it.

Take a look at LED ones. However, some may not be keen on the colour as it is a little too white for some.

You'll probably need to buy one of these in order to find your way around your home after dark.

that progress is being made with low energy lights (I reckon some cyclists should have a dipswitch!)

You can have one or the other but not both.

The fluorescent replacements such as

All the fluorescent of this type will come on within a second (or two if its very cold) but will take several minutes to reach full brightness.

LED R50 lighting is still very poor. You can get quite high output and reasonably narrow beamwidths but the colour quality is very poor. LEDs are inherently monochromatic - they can't directly produce white light so the most common way of producing "white" LED's is to use a blue LED with a yellow phosphor over it. The resulting output is odd (described to me by one person as "gray light") and not many people find it acceptable for things other than walkway lighting.

How well a lamp corresponds to natural light is often measured using its colour rendering index (CRI). Incandescent bulbs are about 100, Compact Fluorescent are a bit above 80 but LED lamps are about 70. It is possible to produce an LED lamp with a CRI of 100 but its luminous efficacy is then only about 16 lumens per watt - similar to that of an incandescent bulb.

And what Peter doesn't say is that currently the best LED elements are about 4W electrical.

Rob

Cool white LED is not an appropriate colour for a lot of circumstances,just as you wouldn`t use cool white fluro in your lounge.

Warm white LED is about but efficiency isn`t very good. Mixing amber or red with cool white is a solution use in some circumstances.

Better white LEDs can push 80 something, good CFL and fluro can go past 90. Colour Temperature, CT in 000s degrees Kelvin is other figure worth looking at , incandescent is warm at around 3200K cold white fluoro can be 4500K very efficient cool white LED might be 5500K very cold colour appearance.

For the OP 40W reflectors efficiency is awful, lamp life terrible and beam control non existent.

LED is an option but far from a low cost one.

CFL/CCFL lamps at this size are not very efficient, cant get all the light from the tube out the front , electronicsare cramped get hot bothered and fail. Not a green alternative.

Low voltage halogen fitting with integral transformer if its a surface fitting with 20W lamps will probably be brighter , more pleasing colour wise, longer lamp life and consume half the power of current lamps.

Adam

Perhaps not. But daylight fluorescent is available. LED, not.

They also make everything a sickly shade of green.

All that does is add in a spot frequency.

For a light to look reasonable for domestic use it also needs a reasonably continuous spectrum output. And LEDs have a long way to go before they'll be this. If ever.

Wouldnt use daylight fluro in a lounge either, theres several daylight varieties as well depending on your latitude.

Er, um, OK fair comment

Yup but it works with well and is the system used in a lot of display devices...

Fluro is very peaky , continuous sort of , but spectral power distribution is like a cross section of the Highlands. Metal halides are worse but rare in domestic settings.

LED is getting an awful lot of research poured into it.

Good white LEDs are a world apart from commodity white LEDs , big brand white LED from someone like Nichia is 20 times price of lowest cost white LED , what do you think ends up in an 18 LED 3.99 GU10....

Adam

Specialist fluorescent tubes are available in just about any colour temperature you want. But not at the same price as the common ones.

It might well be ok for a specific application - but at home you normally want a general purpose device that will provide a good quality of light for anything.

I'm afraid it's a fact of life that higher efficiency comes with those penalties. But good quality tri-phosphor fluorescents will produce good looking light of more than adequate quality.

It is indeed.

I work in location TV drama were an efficient cool running lamp is the holy grail. And LEDs simply ain't anywhere near close yet. Of course they're fine for background effects and have been used for this for years. But not as a key light. Whereas both fluorescent and the various metal halides are - with care. But where power consumption or size doesn't matter tungsten is still the choice. Because the camera doesn't lie. ;-)

It amazes me how gullible the venture capitalists are for the marketing bullshit which spews forth from LED startups.

Rosetta is my favourite ,looks white but has a boosted red , used on fresh meat counters to make the meat lok fresher

In the days when gas was the lighting supply mebbe, hopefully times are moving on and energey saving starts at using lighting suitable for individual tasks or ambience.

This isn`t generally a 25W CFL bang centre of the ceiling.

And good LED fittings can do very well, efficiency being close to fluorescent, installation cost somewhat higher but for commercial clients lot more costs to consider than jsut the install invoice.

Kino Flo and Element Labs both have LED film lighting fittings, seem to be aimed at fitting light sources in otherwise impossible spaces though, inside vehicle cabs etc. Ones I`ve looked at have used white and amber to offer variable colour tempertaure. Don`t think they`re taking over from 18K HMI any time soon though

Adam

Yup.

But Kino Flo make fluorescent soft lights which are near the industry standard. Easy change from tungsten to daylight too.

Lower wavelength LEDs, visible blue being used for excitation presently, and improved phosphor mixtures should see things improve, must admit that first round of `warm` white LEDs are somewhat disapointing and very green,

Adam