Lighting at home

Conrad11 · 3 Jan 2007 at 18:38

Hi,

I have a quick question about enery consumtion and lighting.

When i have a light that can dim, would it cost the same to have the light on full as having it at "half light"?

Everytime i switch on a light, does it cost more money that for the same period of time of it on (if that makes sense?

Thanks.

Jotun · 3 Jan 2007 at 18:41

I believe the dimmer the bulb is the less power it consumes.

Not sure what you mean by your second question.

PlacidCasual · 3 Jan 2007 at 18:55

I'm guessing that an incandescent bulb will not have a linear relationship between current and light output. I would imagine their is a fixed energy input required before it will produce any light and a incremental energy input related to the output.

An example of what I mean, not genuine quoted figures based on empiracl evidence
So it might require 100W at 100% light output
75W at 50% light output and
50W at 0% light output but on the very verge of producing light.

So yes you will use less energy with a bulb at reduced load but the reduction won't be proportional to the reduction in light.

PinkFloyd · 3 Jan 2007 at 18:58

Yeh its something like that.
Most of the energy going into a bulb comes out as heat

Dr.EM · 3 Jan 2007 at 19:00

What PlacidCasual says sounds accurate. Apon switching on an incandescent bulb it requires roughly 10x the running energy (ie 1000W for an 100W bulb) but this is very brief indeed. I suspect you are usually best just turning it on and off when needed

Andr3w · 3 Jan 2007 at 19:00

buy some energy efficiant bulbs, we have about 5 around our house (on in this room) they start dim for about 20seconds then are nice and bright like a normal bulb!