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Topic # 165528 12-Feb-2015 13:51
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I'm not sure if I have given this to anyone on here yet but thought someone might find it useful.

It came about because we were looking to replace our current G9 halogen bulbs with LEDs but I wanted to see what the payback time would be because we needed to replace 25 of them.

You input the bulb specifications, and then the length of time you want to calculate for, the cost of electricity (roughly), how long the bulbs are on for each day, and the number of bulbs being replaced.  It then calculates how many bulbs might be needed over the period, and then the costs involved.

There are also a number of assumptions made which may skew the costs slightly, such as:
- All the bulbs are on for a total of 6 hours per day. If only half the bulbs are on for 6 hours then you could use 3 hours as the total here to be more accurate. Maybe use this on a per room basis to be more precise.
- The wattage of the bulbs should be the average for all bulbs in the house. Some will be higher, some lower. 60W seems fair for an average. See above about per room analysis.
- The lifespan of bulbs is a little vague as each bulb performs differently. A G9 halogen is about 2250hrs, an incandescent standard bulb about 1500hrs, and LED's vary from 10,000 to 50,000hrs hours depending on who you buy them from. I've had bulbs perform much better and much worse than rated, though.

I'm pretty sure my maths is correct but I'm happy to hear if it's wrong.

You can find the spreadsheet here.

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  Reply # 1236563 12-Feb-2015 14:03
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The lifetime of any bulb is vague because the number of times they're turned on and off makes a significant difference. 

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  Reply # 1236574 12-Feb-2015 14:13
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Don't forget that in a residential scenario getting properly "insulation cover" rated LED lights means you can potentially reduce your heating requirements by 50%, according to consumer magazine. "Sealed" halogen lights can actually be 5-10% open, letting a draft in, and not insulated above. That could outweigh the power costs significantly.




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  Reply # 1236629 12-Feb-2015 14:59
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timmmay: Don't forget that in a residential scenario getting properly "insulation cover" rated LED lights means you can potentially reduce your heating requirements by 50%, according to consumer magazine. "Sealed" halogen lights can actually be 5-10% open, letting a draft in, and not insulated above. That could outweigh the power costs significantly.
Absolutely, others should know though that not all led downlights are IC rated. Many aren't in fact. So make sure you check first. In any case in our house all our lights are wall lights so this didn't come into the calculations.

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  Reply # 1237535 13-Feb-2015 18:51
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I had a town house with a house load of annoying halogen downlights - annoying because they were quite fiddly to change, and they blew quite often. I really, really wanted the LEDs t  work - but in the end probably ended up returning 8 out of the 10 I bought,  some blew within a week, others lasted a whole month. 

All I can say I guess they have good marketing, but I'd never go with a LED light again. We  have moved house and I'm enjoying the simplicity of bayonet fittings, and longevity  and cheapness of "normal" lightbulbs

Oh and were  can you buy LEDs for $8? They are $15 at the Warehouse at over double that at a specialist lighting shop




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  Reply # 1237537 13-Feb-2015 18:56
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I have 2 LED bulbs in reading lamps (ebay/cheap and 5 LED downlights in the bathroom (lighting direct/$80). We had a couple of early failures with the downlights but since then, perfect. Perhaps the brand/type you had were badly designed Lissie, I'd happily go all LED.




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  Reply # 1237628 13-Feb-2015 21:29
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We moved house about this time last year and discovered lighting was a large part of our electricity bill.
Had 36 standard bulbs (edison/screw) & 8 halogen (double-ended stainless steel external lights).

Bought 4 LED bulbs @ $8 each from Mitre10, which we evaluated for a month.
Found zero problems and the light was exactly what we wanted.
I then used some credit card points to buy a Countdown card (they didn't do Mitre10 cards).
I then went to Countdown and bought a Mitre10 card and bought the 40 bulbs I needed.

Since doing this, we've saved at least $50/month (sometimes more).

These bulbs are by far the best that I've tried. They claim to be equivalent to a 60W bulb - but I'd suggest closer to an 80W (ie perfectly good for almost all situations).

http://www.orbitlighting.co.nz/product-catalogue/globes/led-globes/7w-e27-a60-led


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  Reply # 1237633 13-Feb-2015 21:36
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Compact Fluroescent is still a decent reliable technology, uses a bit more power than LED but a LOT less than standard, plus they're cheap.




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  Reply # 1237653 13-Feb-2015 22:07
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Quality LED Lighting in Wellington.  Bought more than 30x 14W dedicated fittings in my choice of colour temperature (4000K).  Been going for a year and no issues at all.  None failed, non faded, none flickers.  It is properly certified to NZ standards and each purchase is supplied with a certificate.  The company is run by an electrician that got fed-up with the rubbish on the market.  It was about $55 each, but I think the price had gone up slightly.

I have no relation with the shop, just a very happy customer.




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  Reply # 1237662 13-Feb-2015 22:40
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Do you guys have lights on 24/7 ? I understand wanting an eneergy efficient fridge or freezer - they run all the time - but lights? I'd be astounded if more than 10% of my power bill is lighting. At least with the LEDs, they were instant lights. I'm hoping that the "energy savers" in this house will burn out soon, because I really, really hate waiting for 10 minutes for the lights to slowly warm up. I find I've rapidly adopted the strategy of turning them on when passing in advance of when I need them, clearly defeating the purpose of them.

What's your pay back periof for over $1600 worth  of light bulbs Neil -  I don't think I paid that much on the  light fittings in the last reno I did!




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  Reply # 1237664 13-Feb-2015 22:43
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^^^ must have cheap CFL's the good ones take about 5-10 seconds to warm up

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  Reply # 1237665 13-Feb-2015 22:44
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lissie: I had a town house with a house load of annoying halogen downlights - annoying because they were quite fiddly to change, and they blew quite often. I really, really wanted the LEDs t  work - but in the end probably ended up returning 8 out of the 10 I bought,  some blew within a week, others lasted a whole month. 

All I can say I guess they have good marketing, but I'd never go with a LED light again. We  have moved house and I'm enjoying the simplicity of bayonet fittings, and longevity  and cheapness of "normal" lightbulbs

Oh and were  can you buy LEDs for $8? They are $15 at the Warehouse at over double that at a specialist lighting shop


Sounds like you purchased cheap ones for them to blow, or the driver for them was wrong. I wouldn't buy no name or house brands. With normal E27 or B22 fittings you can get good philips or panasonic LED bulbs that should last many years. I have some and they are over a year old.

Also sounds like you are buying cheap CFLs if they are taking a long time to warm up. Old ones used to take a minute to reach full power, but new ones (non cheap crappy ones) should warm up within a few seconds.

As with LEDs, you get what you pay for.

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  Reply # 1237667 13-Feb-2015 22:51
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mattwnz:

Sounds like you purchased cheap ones for them to blow, or the driver for them was wrong. I wouldn't buy no name or house brands. With normal E27 or B22 fittings you can get good philips or panasonic LED bulbs that should last many years. I have some and they are over a year old.

Also sounds like you are buying cheap CFLs if they are taking a long time to warm up. Old ones used to take a minute to reach full power, but new ones (non cheap crappy ones) should warm up within a few seconds.

As with LEDs, you get what you pay for.


The were for downlights so GU10 fittings - I bought GE brand, when they failed I tried Phillips - same problem. They weren't cheap - as I said about $15 - over 4x the cost of halogens.

The CFLs - I have no idea -  we just bought this house, and there is a quite a mixture of light styles. I guess the thing is with bulbs -  unless you have a house full of chandeliers - you are just not going to get the return on paying much for a bulb. I guess an incandescent is what $2 ? at the supermarket? So to justfify an extra $8/bulb - never mind over $45 - has a huge pay back period. Even if they do work as claimed - which the ones I bought most certainly did not.




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  Reply # 1237668 13-Feb-2015 23:01
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lissie:
mattwnz:

Sounds like you purchased cheap ones for them to blow, or the driver for them was wrong. I wouldn't buy no name or house brands. With normal E27 or B22 fittings you can get good philips or panasonic LED bulbs that should last many years. I have some and they are over a year old.

Also sounds like you are buying cheap CFLs if they are taking a long time to warm up. Old ones used to take a minute to reach full power, but new ones (non cheap crappy ones) should warm up within a few seconds.

As with LEDs, you get what you pay for.


The were for downlights so GU10 fittings - I bought GE brand, when they failed I tried Phillips - same problem. They weren't cheap - as I said about $15 - over 4x the cost of halogens.

The CFLs - I have no idea -  we just bought this house, and there is a quite a mixture of light styles. I guess the thing is with bulbs -  unless you have a house full of chandeliers - you are just not going to get the return on paying much for a bulb. I guess an incandescent is what $2 ? at the supermarket? So to justfify an extra $8/bulb - never mind over $45 - has a huge pay back period. Even if they do work as claimed - which the ones I bought most certainly did not.


I haven't tried the GU10 LED replacements, but had heard that existing transformers can be a problem, as they are made for halogen, and not to driver LEDs. Maybe the 240 volt versions would be better which don't need a transformer, eg the ones that have the LED driver built into the bulb. I am more a fan of conventional E27 and B22 downlighter fittings, with IC rating, where if an LED bulb fails, you just replace the bulb, and not the entire light fitting. Also a big fan of pendant lights.

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  Reply # 1237670 13-Feb-2015 23:05
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We recently replaced a G9 light array with one with 240v GU10 LED's.  The LED's are so much better, pricey sure, but better light and much more reliable. The G9's didn't last long or else always needs a tweak before they'd go.

As for CFL's I wouldn't waste my money.  They can be unreliable and take time light up fully. In our last place we had E27 downlights and never had a CFL last more than a few weeks and we were using name brands.

If I'm replacing incandescent or halogen fittings I'll put in LED's from now on.




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  Reply # 1237671 13-Feb-2015 23:07
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Technofreak: We recently replaced a G9 light array with one with GU10 LED's.  The LED's are so much better, pricey sure, but better light and much more reliable. The G9's didn't last long or else always needs a tweak before they'd go.

As for CFL's I wouldn't waste my money.  They can be unreliable and take time light up fully. In our last place we had E27 downlights and never had a CFL last more than a few weeks and we were using name brands.

If I'm replacing incandescent or halogen fittings I'll put in LED's from now on.


I think the quality of your power supply makes a difference. In one house I was in, the power was dirty and fluctuated a lot, and halogen bulbs were always blowing. The pin connectors on those halogen though are really poor, and often need resitting , as often the bulb hasn't blown, just needs reseating.

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