I was thinking about LEDs used for general lighting.
Personally I don't like them for general lighting, but that is just me.
I will keep my fluorescents until the energy police come and get them.

But here is a idea. (may be)

What if you had a big store like a Walmart and used LEDs for general lighting?
But not the normal LED lighting like today.

What if a lighting fixture was made that used for example: a one foot wide by eight foot long flat hollow aluminum plate with many LEDs affixed to it using heat conducting compound like transistors use to one side only.
The flat side with the LEDs facing down.
The fixtures would be in a similar row layout as used in the Walmart's today.

But...

The fixtures are connected together in series with piping between each flat aluminum plate that a fluid could be pumped through.

The rows of fixtures in series piping and the rows at the ends in parallel piping.

The pumped fluid is then run through a remote fan coil arrangement for store heating in the winter and in the summer switched to vent to the outside air for heat removal from the fluid  so to remove the heat from the lighting fixtures to lessen the load on the stores air-conditioning units.

This way you could run the LEDs at maximum output and they would still be cool and long lasting, plus use the removed heat to help heat the store in the colder months and remove the fixture heat load off the AC units in the summer months.

Plus with the full light output now available from the LEDs, they could be turned upside down and the light reflect off the inside of the fixture to diffuse the light so as not to have that horrible "sparkle" effect.

Energy savings all the way around.
A win win situation.

Would this work?

 

I suppose it would work, but maintenance of the cooling system would be a pain.

I suppose it would work, but maintenance of the cooling system would be a pain.

If the lighting goes out, call a plumber.  

I think the piping will make it too complex and make troubles.
For a good heatsinking just few vertical fins rising from the upper side of the aluminum base would be way sufficient to keep the LED's from being the weak spot in the system (and they will provide a lot of structural strength for the assembly as well, so it won't have to be too thick).
The problem is, such lights are either nonexistent or at least very rare. I haven't seen any similar, except few road lanterns (using such heat management concept), but the road lanterns do not have to operate at so high ambient temperatures and completely still air.

For the light distribution, way sufficient is to keep the output of the individual LED's reasonably low (50lm and below) and better use irregular array (arranged into arcs,...; never a straight rectangular pattern) of them, let's say spaced about 10mm max. Then a prismatic refractor ~10mm below the LED's will make the light completely diffused without any significant light losses.

Using light reflection is quite lossy: Even nice white surface absorb at least 20..30% of light, what is quite a lot, better efficiency you can get only from real mirror, but that does not diffuse the light.


But definitely a dedicated large area/low density fixture will improve both system efficacy, as well as life/reliability of the present day LED's.
The only problem is, the more compact and dense fixture (~3000lm/25*25cm) is just cheaper to make than low density large assembly. But the application can way better utilize the second and ~4x larger area mean just 4x easier thermal management. But 4x higher cost of the "support" (non-LED alone) material. And it is this "support" material (it would have to be the IMS PCB, which is about 4x more expensive per unity area than FR4), what becomes the most expensive component in the LED lighting of today...