True LED savings

Telegraph_Sam

If someone would like to check my mathematics it would seem that substituting a 17 w LED bulb in place of a 23 w low energy bulb would give approximately the same output BUT give a saving of less than a quarter of a penny per hour.  Granted that the price of LED bulbs has dropped there is still a significant price differential plus uncertainty over their likely life.  I am forced to wonder if LED savings have not been rather over-hyped?

burntwood

Telegraph_Sam said:

If someone would like to check my mathematics it would seem that substituting a 17 w LED bulb in place of a 23 w low energy bulb would give approximately the same output BUT give a saving of less than a quarter of a penny per hour.  Granted that the price of LED bulbs has dropped there is still a significant price differential plus uncertainty over their likely life.  I am forced to wonder if LED savings have not been rather over-hyped?

A 17W LED bulb is probably the equivilent of a 150w traditional bulb.
That's wehere the saving occur. Each bulb saving over 130w per hour, and if we assume a domestic light is on for say 8 hours per day (although probably not at this time of year) that's 1 kWh saving per bulb per day. - so about 15p/day/bulb saving on a typical tariff.

Of course if you already invested in having a low energy bulb fitted, then the saving will be less.

So unless you have cause to change the existing low energy bulb you have invested your hard earned cash in, why would you?

Sorry if I am wide of the mark. I'm not sure what other 'hype' you could be referring to.

MWT

Telegraph_Sam said:

I am forced to wonder if LED savings have not been rather over-hyped?

Against CFL the 'saving' is in lifespan, not power and so you just replace the CFL with LED when it fails.

The energy saving against incandescent and Halogen as burntwood explained.

In my case I replaced 10x50W halogen with 10x5W LED, that gave me a saving of around 3-4kWh per day, still takes a while to cover the cost, but a much shorter time period than CFL vs LED.

Gerry1

MWT said:

Against CFL the 'saving' is in lifespan, not power and so you just replace the CFL with LED when it fails.

In my experience it's the other way round, at least for conventional A-shape bulbs.  Filamentary LEDs consume about 10% of their incandescent equivalents, e.g. 6W for 806 lm, equivalent to 60W.  In contrast, here's a CFL that's 14W for 820 lm !  No wonder few if any CFLs are still being made.

However, LED lifetimes can be dire when operated cap upwards, especially in semi-enclosed or closed fittings.  They're still cost effective compared to incandescent, but I've had several Osram 94/100W equivalents that have failed within a few months, and they weren't left on for long periods.

matelodave

IMO if you've already got CFL's and can put up with the slow start time and poor colour then there's, no real advantage in changing them for LED's but there's no contest where you can replace incandescent's with LED's as they'll save between 80-90% of the energy.

We've got 3 CFLs in the hall which are rarely used so there's no point in changing them but the rest of the lamps in the rest of the house have been all swapped from incandescent to LED's. The biggest saving being in the kitchen where 10 x 50w halogens (500watts) has been reduced to 10 x 4watts = 40watts . The lounge now only has about 20watts of LED's instead of around 300w of incandescent's. The 500w outdoor floodlight has been swapped for two 10watt LED's as well.

Talldave

Since moving to our current place last summer, I've replaced 76 halogen bulbs with LEDs, saving 2430W.  A few of those are AR111s where the savings are not so high, but the number of lumens has gone up!

avoidtheupsidedownbottles

One thing I like about the old 'stick' CFLs is that when fitted in a hanging pendant, the light comes out sideways giving a more diffuse feel, rather than like a harsh directional downlighter.

matelodave

Talldave said:

Since moving to our current place last summer, I've replaced 76 halogen bulbs with LEDs, saving 2430W.  A few of those are AR111s where the savings are not so high, but the number of lumens has gone up!

We cant manage that, but out of 55 individual bulbs (some are in fittings with multiple bulbs) we've 52 LED's and 3 CFL's and no incandescent's. I haven't added all the kw savings as most of them don't get used ever so often but it's in the rooms like the kitchen, lounge and study where we save most because they are on for the longest.

The other benefit is that we've not had to replace any of them in the past eight years.Especially in the kitchen, bathroom and study where there are  GU10's.  The halogens didn't last much more than about six months (frequently less)

st999

I saved about 40 watts per hour replacing my 32 inch CFL backlit TV with a 49 inch LED backlight TV.
Same with my computer monitor.
Old TV 100 watts, new TV 60 watts.
Old computer monitor 60 watts, new computer monitor 30 watts.
Also since replacing all my light bulbs with LEDs I am using 1000 kWh plus less electricity a year overall.

MWT

matelodave said:

The other benefit is that we've not had to replace any of them in the past eight years.Especially in the kitchen, bathroom and study where there are  GU10's.  The halogens didn't last much more than about six months (frequently less)

That is interesting, the GU10's I replaced with LED's had all been in place for 20 years with zero failures.

I still had the pack of 5 replacements that I bought at the time they were installed, untouched.

Each one had its own individual transformer though. Certainly couldn't complain about lifespan...

matelodave

GU10's are 240v so yours must have been MR11's which are 12v.
We live out in the sticks and our power come via miles of overhead cabling to a transformer which just feeds a couple of houses from the high voltage (I guess 11kv network) and we seem to have around 248-250v most of the time which probably over-runs the GU10's. When we did have MR11's fed via a transformer in our previous place they also lasted for ages