On Sep 24, 1:21*pm, Peter Parry wrote:
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 athttp://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-...26W-PL-Lamp-pr...

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.

You can use a single high up light source, but it will put you in hard
shadows wherever you go. You lso need to put it high to get a
reasonable light distribution and size of light pool - and that makes
relamping a right pain. And you've only got one lamp, so total
darkness when it goes.

A few ordinary domestic sized CFLs at wall light level would give more
pleasant, softer light, the light sources would look far nicer, and
you've got no relamping issues, and no chance of being left in the
dark. Put them among foliage and they look rather nice. Not quite as
efficient as halide but much nicer to live with


NT