On Tue, 23 Sep 2008 23:57:02 +0100, "Toby"
wrote:


I am after the most energy efficient lamp that is practical to illuminate a
patio area, a 500w halogen does the job well, but is 500w, obviously.

Have a look at http://www.lo-energilighting.com/ecoflood.html
I had some of these fitted to a warehouse to provide illumination
around it a few years back and they are remarkably good with very even
light coverage.

http://www.lo-energilighting.com/ecoflood.pdf

The Midi version might do what you want.

I am not bothered if there is a few minute warm up time, as I won't be using
it for PIR activation, just general use when having a BBQ etc.

They take 5 min's or so to get up to full output but are useable
immediately they come on.

My options seem to be, stay with a standard 500w halogen, go for a
fluorescent like this
http://www.qvsdirect.com/Low-Energy-...-pr-22878.html

I've used the cheaper CFL floodlights (Screwfix one) and found they
have nowhere near the effective output of the eco-flood using the same
lamps.

What is the average lamp life of these units, and the approximate halogen
equivalent light output?

The Lumens per Watt of the lamps themselves is in the order of :-

Linear Halogen -16; life 1,000 to 2,000 hrs
CFL - 55; life 6,000 to 15,000 hrs
Metal Halide - 82; life15,000 hrs however this drops with frequent
runs of less than 10 hours. At 2 hrs per start its is about 6,000
hrs.

For floodlighting the reflector becomes important as cheap fittings
often have poorly designed reflectors with a lot of overspill of light
into unwanted areas and poor evenness of light which makes the
illuminated area appear subjectively darker than it is (the eye tends
to adapt for bright spots).

The colour temperature and colour rendering index of Metal Halide is
generally considered to be better than that of CFL which is usually a
bit "cold" and is broadly similar to incandescent lighting.