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Energy Assessment: Switching off lights

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      CommentAuthorSteamyTea
    • CommentTimeDec 15th 2010 edited
     
    Posted By: Paul in Montrealconverted to IR and will thus radiate everywhere in the room

    Very diffused though and I suspect barely measurable especially after convection and conductance have done their work.


    Posted By: DamonHDUsing a heat pump would take maybe 1/3rd kWh of electricity to generate that 1kWh of heat,

    Yes was not really thinking of a heatpump, excellent for a continues heat load, not brilliantly controllable in my experience and certainly not very scalable (multi small heat pumps may well be the answer).

    If we had gas here I would be on it, but had a quote of £20,000 and then another £7000 to fit a system. As we are 'greening the grid', all be it very slowly, this issue of CO2 goes away in time. With 3 wind farms pretty close to me my conscience is clear (wont mention the big diesel plant at Indian Queens and The Scillies, my nearest FF generators) and the rest coming from the new gas plant in Plymouth and the old faithful at Hinkley Point. Be interesting to do an energy mix map of the UK and plot the data against energy use, see if price really does have an impact.
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      CommentAuthorDamonHD
    • CommentTimeDec 15th 2010
     
    Paul: switching off the lights saves money *AND* CO2 almost however you heat, in the UK.

    (And as Wookey points out, in summer, it's double sensible to have efficient lighting and turn it off when not in use, to avoid paying for more energy to pump the unwanted heat out of the building.)

    If you have a massively inefficient fossil-fuel boiler than replacing heat from it with massively-inefficient waste energy from electric lighting might be better, but then the problem is the inefficient heating system, which should be replaced in any case.

    Rgds

    Damon
    •  
      CommentAuthorDamonHD
    • CommentTimeDec 15th 2010
     
    BTW, even with an increasingly green grid kWh, it's still better to get more out of it with heat-pumps to save it for other purposes such as lighting and transport and so on.

    Rgds

    Damon
  4.  
    Posted By: SteamyTeaVery diffused though and I suspect barely measurable especially after convection and conductance have done their work.
    It's not zero though and it's not lost. But the amount from light is indeed small - it's all the byproduct heat from the inefficiency of the bulb that's also usable - more for incandescent, less for CFL/LED.

    Posted By: DamonHD(And as Wookey points out, in summer, it's double sensible to have efficient lighting and turn it off when not in use, to avoid paying for more energy to pump the unwanted heat out of the building.)
    Fully agreed - and for all outside lights too (in any climate). One nice thing in summer is the reduced amount of time that lights are needed.

    Posted By: DamonHDIf you have a massively inefficient fossil-fuel boiler than replacing heat from it with massively-inefficient waste energy from electric lighting might be better,
    The waste energy from lighting is not "inefficient" at all - but it's not an effective use of the electrical energy. Resistance heating is 100% efficient, but a heatpump has an apparent efficiency of 200-350% (depending on many factors).

    In the long term, it makes sense to move away from the use of fossil fuels for heating. Electricity will become pretty much the only form of energy that's easily transportable from point of production to point of use. That day might not be here yet, but it will be eventually.

    Paul in Montreal.
  5.  
    Posted By: DamonHDBTW, even with an increasingly green grid kWh, it's still better to get more out of it with heat-pumps to save it for other purposes such as lighting and transport and so on.
    Couldn't agree more. Especially over here with close to 100% hydro - the less we use, the more we can export and displace coal-fired power stations in New England.

    Paul in Montreal.
    • CommentAuthortony
    • CommentTimeDec 15th 2010
     
    Remember guys that we are considering a heated building so the summer discussions are not relevant.
    • CommentAuthorRobinB
    • CommentTimeDec 15th 2010
     
    Wookey, I don't know what the consumption is - I've asked them. Too difficult for me to isolate it. I did get put off some PIR lamps which had a standby of 7w. This PIR is tiny so I'm hoping it consumes less. It's certainly not noticeably heating the building!
    RobinB
    • CommentAuthorCWatters
    • CommentTimeDec 15th 2010 edited
     
    Are the curtains open or closed? How big are the windows?

    If light escapes presumably the light bulb is less efficient at heating the room.

    :bigsmile:
    • CommentAuthorwookey
    • CommentTimeDec 16th 2010 edited
     
    Posted By: tonyRemember guys that we are considering a heated building so the summer discussions are not relevant.

    Of course they are - do you change your bulbs to different, less heat-emitting ones in summer?

    No, so justifying hot bulbs by winter-only performance is silly. You need to consider the whole system over the whole year to get any sort of useful answer.
  10.  
    Posted By: wookeyOf course they are - do you change your bulbs to different, less heat-emitting ones in summer?
    It's lighter earlier and later in the day in summer, obviating the need for lights compared to the heating season ... though, in the UK, the summer can also be in the heating season too :P

    Paul in Montreal
    •  
      CommentAuthorDamonHD
    • CommentTimeDec 16th 2010
     
    When I used to live in Edinburgh, at least one year I was waiting and waiting for summer, just around the corner ... and then I realised it was September... %-P

    Rgds

    Damon
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 16th 2010
     
    Edinburgh
    Sometimes the sun gets to 30 degrees in the sky up there, why all the Celts moved here 200 years ago.
    • CommentAuthorRobinB
    • CommentTimeDec 16th 2010
     
    Wookey, got this reply from the supplier "Hi there, it's actually on the instructions.
    Its 0.9W standby consumption very minimal. " This is for those lightbulb with mini built in PIR. Of course I don't have the instructions. For me it's worth having it switch off.

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