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Joined: 05 Feb 2007 Posts: 841 Location: West of Melbourne
Can someone tell me if there is much difference in running downlights as opposed to a regular light bulb in terms of energy usage and cost?
For example, on our house electrical plan there is one light for the sitting room, which we will replace with 4 downights. Does this mean we would be using 4X power or are downlights more economical and therefore be no different to running one regular say 100W globe?
I don't like downlightes because of the, at least perceived, extra power costs.
If you want to find the power differnce it's not too complicated.
Look at the wattage of each alternative. However, keep in mind that if you use a transformer (low voltage lights) or ballast (flourescent light) then you need to add the losses in these components. You can get electronic ballasts and "switch-mode" transformers that are more effecient.
Once you've done the sums, I'd like to see the results.
Also, you'd want to make sure that you're getting the same light output otherwise you're not comparing apples with apples.
Joined: 05 Feb 2007 Posts: 841 Location: West of Melbourne
Ok, I just ducked to the supermarket, and from what I can see there, there are only 50W downlight globes.
There are 12V and 240V varieties - presumably 240V replaces a regular light fitting, whereas 12V run off transformers?
Would it be accurate to say then that 2 downlights (50W) = 1 regular 100W globe in brightness? And that 20 x 12V globes would use the same power as 1 240V globe?
1) 240V globe replaces a regular light fitting? YES
2) 12V globes run off transformer? YES
3) 2 downlights (50W) = 1 regular 100W globe in brightness? YES, if the globes use the same technology and they are both driven by the same voltage. The available technologies are:
* normal incandescent
* quartz halogen (somewhat more efficient then normal incandescent)
* fluorescent (most efficient)
There are other technologies (mercury vapour, sodium vapour, etc), but these are rarely used in residential applications. An emerging technology for residential use is LEDs. Very efficient, very long life, expensive, but that is a whole other topic.
If the bulb is driven by a different voltage then you will get some losses.
4) 20 x 12V globes use the same power as 1 240V globe. NO. Power is measured in Watts, not Volts (Power [Watts] = Voltage [Volts] x Current [Amps]. The simple answer is, forget the voltage of a globe, just look at its wattage.
If you're after maximum efficiency, you can't go past compact fluorescent tubes (particularly those with a fixed electronic ballast, as opposed to a ballast integrated into the globe.)
The key things to remember are:
1) Power consumption is measured in Watts. Forget volts.
2) Light output is measured in Lumens (sometimes stated with the product). You can just look at a globes output and get a subjective feel for how much light it puts out.
3) If there is a separate transformer or ballast then you need to consider how many watts it is also consuming/wasting.
Joined: 05 Feb 2007 Posts: 841 Location: West of Melbourne
Nope - very informative.
I did a bit of a search this afternoon, and found that the halogen downlights are energy wasters.
Like you say, the efficient ones are compact fluorescent and LED's.
Does anyone know if you can put either of these on a dimmer switch, and/or whether it is worth it.
We had planned on having 26 in the portico, entry, sitting, hallways, kitchen, family and dining areas - so they will be used a fair bit.
Joined: 10 Sep 2006 Posts: 48 Location: Melbourne, Victoria
To my knowledge, the fluorescent lights (CFL included) are traditionally non-dimmable. However, I believe now there are some dimmable CFLs available in the market, but they cost around $22-25 a pop. Pretty sure Beacon has them.
Also you will find most literatures say that an 11 W CFL produces the same brightness as a 60 W incandescent globe, 20 W = 100 W, etc. Which is why fluoros use up less energy. Plus they are longer lasting.
From what I can gather, you're after a light that is attractive, energy efficient and dimmable. My suggestion is a compact fluorescent with separate electronic dimmable ballast. You can also get different colour temperatures from warm to cool.
I think downlights look better and I'm thinking of combining the suggested compact fluorescent with a separate electronic dimmable ballast with some low voltage downlights over the kitchen island bench etc. These are mainly for show when guests come over and would not be relied on for providing the required lighting.
I'm also thinking of getting some tri-colour LEDs in the entrance lobby. These lights let you change the colour to anything you want. So one day you can have purple, the next day red. I'll probably get bored of it after a few months but it will be fun for a while.
I'm an electrical engineer. However, there's a designer in there somewhere trying to break out. I've done a “reference” design for my new house but will get an architect to put together a design before any cross-fertilization of ideas. Archicentre appear to have a nice new house design report service that will put together concept design for about $2000.
Looks like your quest for energy efficient lighting is very current affair. I heard on the radio this morning that Australia will be banning incandescent lights in a few years (the first in the world).
Although they mainly do edison screw (ES) they also have a few Bayonet Connection (BC). Note some of the lower powered dimmables have an 18000 hour life - that is 18x the life of a filament lamp, so bear that in mind when costing.
For economical down lights, you can investigate LED downlights. These have recently begun to come onto the market. I would suggest getting ones based on Luxeon star leds as they are just about bright enough whereas the standard super brights are a bit too weak and focused for my liking (even with an array of 50 of them in the bulb). You will probably find these on ebay.
Not cheap by any means but will probably pay for themselves pretty quick in efficiency and long life. They claim a Long operating Life ~35,000 hrs but then they also admit to 10 or 30 degree (standard) beam spread - you can get up to 50 degrees on standard halogens. They do however give out 120 Lumens which is quite high for LEDs (A standard 100 watt incandescent light bulb emits approximately 1700 lumens)
So you would need to have about 15 of these to really get the same light.
Lighting design is a lot about compromises and usually it is efficiency that gets turfed first followed closely by price.
It's worthwhile to note than in downlight applications, the directional beam of LEDs is useful.
Traditional downlights send most light downwards by using a reflector. Dichroic downlights let the heat pass through the reflector into the roof space, while reflecting the light downwards. This way the light beam is cooler, but you still get waste heat generated.
LED downlights don't generate as much heat as traditional DLs. So you can cover them with insulation in the roof, which you MUST NOT do with traditional DLs. This means LED DLs are better for insulation efficiency.
The new Luxeon superbright LEDs are up to about twice the efficiency of a normal bulb, if you are trying to illuminate a whole room evenly. However, if you want the brightest area on eg the kitchen bench, and you don't need the rest of the room so bright, then you will definitely gain from using this sort of lighting. Up front costs are high, and payback on a light used from 6pm-10pm every day is about 3-4 years. You also need a better regulated transformer, which is designed for LEDs, so you don't overdrive the LEDs and wear them out in 10,000 hours instead of the rated 50,000. LEDs mostly don't blow, they fade over time.
In short, they are great, and will save you money when used in the right place, particularly when you include the ceiling/roof insulation efficiency improvement.
I take back what I said about covering the LED DLs with insulation being OK.
There is no heat in the light beam, but there is heat generated in the unit.
I don't know how much, so you should check before covering them with insulation, so you don't start a fire.
Joined: 05 Feb 2007 Posts: 841 Location: West of Melbourne
I paid a visit to Beacon lighting today and asked about the compact fluorescent globes for downlights.
The lady showed me 2 alternatives...
1) Purchase a standard downlight (MUST BE 240V, NOT 12V) for approx. $10 and replace the globe with a megaman(?) CFL approx. $20. Total cost $30 per light. In this case, the globe has the glass cover similar to a downlight, so it is all flush with the ceiling.
2) Purchase a pre-packaged CFL downlight kit for approx $20 ea. In this case, the CFL globe (spiralish) sat in the downlight housing flush with the ceiling, with a piece of round glass hanging approx 1-2cm from the ceiling that sort of diffused the light. These did appear slightly larger than a standard halogen downlight fitting.
Both instances looked very contemporary and sleek.
Moral of the story -
It isn't much more expensive to install CFL downlights to the regular halogen downlights, yet the savings will amount to hundreds - possibly thousands (considering the number we intend to install) in energy bills and bulb replacement costs.
We will now get our builders to hook up the 240V points, and we will purchase and get the CFL's installed after hand-over. Funny part is that the builder was charging $45 for each downlight fitting anyway - so with them costing $20-30 ea and a sparky in the family I think we'll be laughing
The dimming mechanism is odd. Neco state "brightness can be adjusted from 100% to 66%, 33% or 5% with consecutive switching OFF/ON action". Looks like you flick the on/off button if you want them dimmed. ????
Thanks for providing the link - I will definately be pursuing this avenue for lighting my new home - does anyone know of any alternative brands with this style of CFL downlights?
Joined: 18 Jan 2007 Posts: 240 Location: COUNTRY VICTORIA
I'm still confused!!!!!
I spoke to Beacon lighting who indicated yes they have an 11w globe you can repalce the normal globe with after installation and maybe one a week if we wanted to. But then they are not dimmable.
Then I called them about dimmable ones and they said there is some coming in that are dimmable but the cost would be approx $60, obviously this will get cheaper as they get their own or can get from another loacal supplier (maybe).
My electrician said he was not a fan of the 11w ones as they are not very bright and give off that yellowish light. Is he just being difficult?
The only reason I would like dimmable is for looks, I like the way a room can look when you dim it down.
I have my final Electrician meeting on Thursday so any info possible would be appreciated as I'm not sure which way to go.
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