Energy efficiency of these bulbs?

[JohnW2]

err, no. The bulbs would fail after around 1000 hours or six weeks leaving the costs at around £50. Still worth remembering to turn the light off though. LED equivalents say 2 by 10watts would also cost around £50 over a year 24/7.

That's rather misleading.

If a bulb comes from a batch which has a median expected survival time of 1,000 hours, then one would expect about half of them to fail at/by 1,000 hours. However, as for the other half, it's just a gamble - there's nothing about a median survival of 1,000 hours which precludes the possibility of some lasting much longer than that (maybe 10,000h, or more) - and, as has been said, one would expect very long life to be much more common in a bulb that was permanently on, rather than repeatedly being switched on/off. In fact, I would say that it's pretty (maybe very) unusual for an incandescent bulb to fail other than at 'switch on' (when the reason for failure is pretty obvious).

 

[SUNRAY]

err, no. The bulbs would fail after around 1000 hours or six weeks leaving the costs at around £50. Still worth remembering to turn the light off though. LED equivalents say 2 by 10watts would also cost around £50 over a year 24/7.

Leaving almost any electrical device on will invariably extend its longevity. One church I know of leaves a 40W incandescent on permanently. I supplied a box of 25 bulbs a number of years ago, I'll guess~10, the last time I climbed up and changed one there was over ½ box left. I'd say it averages 1 per year or better.

At school as part of a project we measured a building and drew plans, we had several attempts at measuring one area as we seemed to end up with an unexpected void adjacent to the deputy headmasters office.
Loads of banging on walls (lathe & plaster) found an area the size of a door sounding different, coinciding with a length of different skirting board. Outside there was a small window, maybe only a little over one foot square.
It took a while but eventually it was agreed the skirting could be removed and a hole could be cut. The maintenance man did the deed and passed a wandering lead lamp through and looked with the aid of a mirror. The headmaster had a look and instructed to cut out the plywood board to reveal a room something like 12ft square... the light was on, albeit totally blacked by dirt, and had therefore been on longer any member of staff employed there, something like 30 years.

 

[winston1]

A permanently on incandescent - without the considerable heating up / cooling down it would not surprise me if they lasted a good few years permanently on.

Good in theory. Several years ago lights got left on in late mothers loft. Next time I went round all three bulbs failed.

Another case a place where I worked had 3 incandescent lights at one end of the stores on 24/7 in addition to fluorescents elsewhere. It seemed the incandescent were always blowing.

 

[ericmark]

In the main I changed to CFL then LED to reduce maintenance, and @winston1 says, the tungsten bulb had a short life, and will maybe 15 bulbs in the home, one or another was going once a fortnight.

But as to energy saving, I actually wrote to the energy saving trust and asked if they included the inferred heat in the home which means the air temperature can be dropped a couple of degrees in the evening, did the so called energy saving bulb actually save energy when used in doors in a heated room, and they admitted that no survey had ever been carried out, so on average through the year in a central heated room we simple have no idea if the so called energy saving bulb saves any energy, specially if we include manufacturer.

The more to bulbs with a longer life span has caused a problem for me, where I have a draw full of spare bulbs, brand new, but it will likely take longer than my life time to use them all, it did not help when we stocked up on tungsten bulbs before they were withdrawn, then moved to E14 bulbs rather than BA22d so very few places they are still used.

However neither the CFL or the LED produces much inferred heat, when I moved from tungsten to CFL I found I wanted the main living room warmer in the evening than during the day, my central heating was on a time switch, so came on in morning and off when we retired to bed, this needed changing so instead I had a programmable thermostat and the temperature was set 16°C over night, 18°C in the morning, and 20°C in the evening, once this was done returning to tungsten was pointless.

The big change was the kitchen, where we for years had no heating, the problem was more about keeping it cool, so had always been the fluorescent tube, which to get spread of light fixed size, a 65 watt, then a 58 watt tube, however brighter than required so when the LED came out reduced to 22 watt, however also a reduction in the amount of light, then we got an induction hob, so less heat into the room, the oven better insulated, even the kettle boils just one cup of water, so for the first time looked at heating the kitchen.

The difference between our house and father-in-laws house which was next door but one, due to him using gas and us using electric to cook with what huge, he had a very damp kitchen and needed to open the roof light to remove the moisture and out kitchen was much cooler and drier, automatic boil then simmer on the hobs did help.

I think back and wonder how they got away with a house with a gas supply for the cooker, and no cooker hood? No one seemed to worry in late 70's.

But my main point you can't take one product in isolation, one has to consider how it works as a whole, does the tumble drier remove air heated by the central heating or cause a depression in the house and draw in fumes from any fires in the house, be gas coal or wood.

My utility room is not heated, so I can simply put a pipe out of the window for tumble drier, leaving window open so dryer air than in main body of house is drawn in to replace the air used to dry cloths without losing heat from house, however I know next one will likely have a heat pump in it, so not bothering drilling a hole in the wall.

We all tend to relate to what we have, when I lived in an open plan house, I could see no point in TRV on radiators down stairs, but when I went to mothers house with doors between every room, this was completely different. There is no general rule, one has to consider ones own home, and how it works in that home.

 

[bernardgreen]

they admitted that no survey had ever been carried out, so on average through the year in a central heated room we simple have no idea if the so called energy saving bulb saves any energy, specially if we include manufacturer

There was a survey / investigation about 10 years ago. The result was that both the heat and infra red radiation from incandescent lighting were found to be a significant contribution to comfort in the room.

The results were not made public as the aim of the survey was to prove the theory that LED lighting was the best option but the results did not support that theory.

 

[winston1]

In the summer we certainly don’t need extra heat from incandescent lamps.
In the winter such additional heat is the most expensive money can buy. Electricity is four times the cost of gas.

 

[JohnW2]

Electricity is four times the cost of gas.

I think you are behind the times. With gas prices soaring but only about a third of UK electricity being generated from gas, the differential has reduced, and probably will continue so to do - not to mention the fact that, in the long-term, the days of gas are 'numbered'.

 

[SUNRAY]

There was a survey / investigation about 10 years ago. The result was that both the heat and infra red radiation from incandescent lighting were found to be a significant contribution to comfort in the room.

The results were not made public as the aim of the survey was to prove the theory that LED lighting was the best option but the results did not support that theory.

I haven't seen the report but it makes good sense to me. In theatreland the reduction in incandescent lighting has seen the cost of heating spiralling upwards and not in proportion to the reduction of lighting costs. One theory is the perceived warmth from non white lights is the cause, however not much stage lighting is done without some sort of colouring.

 

[winston1]

My electricity is still 4 times the cost of gas. 50 years ago it was double and the differential has gradually widened. I cannot predict the future. Gas is so entrenched in society I doubt it’s days are numbered though.

 

[JohnW2]

The result was that both the heat and infra red radiation from incandescent lighting were found to be a significant contribution to comfort in the room.

At least some of that 'comfort' is probably psychological (due to colour of light) and/or due to the fact that the IR component heats people, rather than the room.

However, at least in financial term, any perceived 'benefit' during winter months is likely to be at least 'cancelled' by the wastage of energy during the rest of the year.

Kind Regards, John

 

[JohnW2]

Gas is so entrenched in society I doubt it’s days are numbered though.

Who knows? - and the 'phasing out' will certainly take a very long time. However, my understanding is that we are only three years away from the time when the installation of gas (or oil) boilers in new-builds will be 'banned', so we have certainly started moving down that path.

In common with a good few other places, the village in which i live does not have piped gas - and, now, I presume that it never will.

 

[ericmark]

In the winter such additional heat is the most expensive money can buy. Electricity is four times the cost of gas.

Two problems, one I don't have gas, and two even if I did, have a perceived 2°C temperature increase when lights are on, means the room is 2°C cooler when lights are off, which could amount to 10's of hours at the lower temperature, with only a couple of hours at the higher temperature, so even with 4 times cost, tungsten bulbs can be cheaper due to time scale they are used for.

Even in summer, due to lights being used less, it seems unlikely it will use enough extra electric to be worth swapping for LED for the summer.

However where the tungsten lamp fails, is when the room is so hot we need to cool it, be it a tungsten bulb or any hob other than induction, we don't want the room that hot we are eating our sweat as it falls on the food we are cooking, and some people went OTT with silly little spot lights which would heat the room far more than 2°C. Even found where the 6 amp MCB had been changed to 10 amp as with the quartz halogen lamp it was using so much power.

The Next shop I worked on doing a refit had no heating in the store, it was all from the lights, and massive air conditioning units to keep the store cool, it that case LED lights would have saved a fortune, there is an exception to every rule, but in the main tungsten lights in the British home saved energy over LED lamps, may be not money, but did save energy.

 

[JohnW2]

... have a perceived 2°C temperature increase when lights are on ...

Unless your "lights" were many and/or large, I have to say that I find that surprising and, in any event, wonder how long it took for that 2º rise to occur?

Kind Regards, John

 

[ericmark]

Time wise first few seconds, since we get the inferred without heating the air, it is perceived, one can't get a thermometer to measure it, and even the colour of our cloths will make a difference. And of course leave the curtains open and it can travel through the window out just like the sun comes in.

I found after fitting CFL I wanted the heating 2ºC higher at night, during the day I was doing enough to keep warm, only when sitting down and watching TV did one feel the room was too cool. The room had two chandeliers each with three bulbs normally 60 watt each, so it is 360 watt.

We also had a gas fire, 4.5 kW but could have 2 or 4 segments heated and adjust how much heat, again inferred heat as well as convected, but the problem was no thermostatic control, so room would slowly get warmer and warmer, and one would not realise how warm it was.

The gas central heating used a Myson fan assisted radiator which although not noisy, one could hear it, and as the central heating turned off the fan would stop turning so you felt cool, in contrast my mothers house had a condensating boiler that turned up/down not on/off, and the radiators were controlled with TRV's, so one had nothing to show one if heating full on or just ticking over, it may have been the lack of any hysteresis, but one did not notice when heating went off, until it had been off some time.

I was surprised how long it took the house to cool, mother liked it warm, so 22ºC at 10 pm when carers put her to bed, it was set to cool to 16ºC at which point heating would come on, but most nights at 7 am when heating set to raise to 20ºC well actually set to 22ºC for an hour then back down to 20ºC as the TRV anti-hysteresis software was OTT, but at 7 am it had rarely cooled to 16ºC.

So over 9 hours the temperature had not dropped 6ºC, would not be linear, but it raises the question of have programmable TRV heads, as it takes so long to cool.

So if warming the room air an extra 2ºC in the evening, from 6 pm to 10 pm, it will still be 2ºC and 1ºC over the setting used when heating supplemented with inferred at 2 am, so extra heat escaping for 8 hours even when room temperature only needs boosting for 4 hours. Basic thing is extra heat is escaping unit the air temperature is low enough to start the boiler, which is when it drops to 16ºC or 7 am which every happens first.

But one can't quantify the loss, and there is no argument LED bulbs last longer than tungsten bulbs, not only is there the cost of renewing bulbs, in price of bulb, but also the cost in time for some one to replace them, and the LED looks better too, yes we had display cabinet lights in the days of tungsten, but they did not look like this with the colours changing by the minute, yes don't need the light to see by, but it does enhance the display. The same goes for down lights, they are not good to see with, but look better than a fluorescent strip light.

 

[big-all]

its so so difficult to apportion any heat gain to any one action unless you have only one input changing you have no way to isolate the gain from each source
a human for example could add no to perhaps 250w an hour to a room dependent on sedentary or very active actions
a room with a light bulb on may not be the only added input a tv or fan a moved curtain or even air flow through an open door will effect results
we all have our own often wrong assumptions, not through ignorance but through misled perception through probably age dictating our thought are often blinkered and not open to the actual information giving the actual situation