Walmart to use LED lights....

[DrJ]

..."LED lighting is one technology the company will deploy more widely, for example. Those lights will replace fluorescent tubes in freezer and display cases, resulting in 50% energy savings and longer life expectancies."....

http://articles.moneycentral.msn.com...enWalMart.aspx

[winny]

That's pretty strange. T5 HE tubes manage about 105 lm/W whereas the newest Cree can do ~130 lm/W when severely underdriven. Flourescent tubes are much cheaper per lumen than LEDs, but perhaps if you have high costs replacing them, LEDs would be better.

Oh, and LEDs color rendering is horrible compared to fluorescent tubes. The groceries will look awkward.

[Wim Hertog]

Originally Posted by winny

That's pretty strange. T5 HE tubes manage about 105 lm/W whereas the newest Cree can do ~130 lm/W when severely underdriven. Flourescent tubes are much cheaper per lumen than LEDs, but perhaps if you have high costs replacing them, LEDs would be better.

Oh, and LEDs color rendering is horrible compared to fluorescent tubes. The groceries will look awkward.

In freezers and fridges LEDs are actually much better than fluorescents. T5's have an optimum working temperature of 35°C or something. Go below that and the efficiency drops dramatically.

The color temperature on the new Cree LEDs is comparable to daylight fluorescents (5000K-6500K) and the CRI is 80. Triphosphor tubes manage to get between 82 and 85, which is more or less the same and the difference is not really noticeable.

[NewBie]

winny,

Consider that fluorescent bulbs need to run warm or the become highly inefficient. Also consider where the light is going, and the large losses of common reflectors. Then toss in ballast losses. Ice it off with having to cool the considerable extra heat produced by fluorescent bulbs when you cool them.

More info here, including links to the devices:
http://candlepowerforums.com/vb/show...hlight=walmart

[Unforgiven]

We'll follow NewBie's link and continue discussion there.

Thread closed

Unforgiven