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Energy Assessment: LED savings

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  1.  
    • CommentAuthortony
    • CommentTimeNov 7th 2020
     
    I have just done a consultancy on LED lighting and commensurate savings

    Unusually two regularly use spaces one a gym and the other a art area both remote from the other buildings and both with radiant electric heating.

    In both cases I rejected the winter savings on heating, can you see why?

    I have a very interesting semantic point on LED and it is true too --  when the energy rating of lighting is reduced less heat goes into the building as lost heat from lighting (saved on electricity bill) BUT in the heating season this heat was reducing the demand from the heating system and so not all of the savings attributed to LED are genuinely available, there is often a cost saving but it will be the difference in cost between electrically produced heat and oil or lpg heat which is delivered cheaper per kWh output.
    In the space with electric radiant heating there is no saving for changing to LED !!!!!
    • CommentAuthorMike1
    • CommentTimeNov 7th 2020
     
    It's a shame they weren't interested in analysing their CO2 impact too.
    • CommentAuthortony
    • CommentTimeNov 7th 2020
     
    They are, I am more interested in the economics but 250kWp of solar going on gshp and ashp to replace fossil fuel boilers - grant applied for to help fund it. The other consultant record 500t CO2 presumably p/a
    • CommentAuthormuddy
    • CommentTimeNov 7th 2020
     
    Led lighting is lower maintenance, and has much neater luminaires.
    • CommentAuthortony
    • CommentTimeNov 7th 2020
     
    I am not anti LED lighting and love the electricity they save, I hate it when they are specified at too higher temperature spectrum and too bright.

    My hobby is reducing energy use 🙂
  6.  
    Sounds like good work to consult on your hobby! Interesting project.

    The Radiant heating in the gym is maybe chosen to get the heat downwards, to where the people are, without needing to heat the whole building. Wouldn't heat from incandescent light fittings just rise up to the roof 30 feet above everyone's head?
    • CommentAuthortony
    • CommentTimeNov 8th 2020
     
    I have heard that argument before but don’t buy it certainly not for normal rooms, there will be an element in the gym/dance studio which has a double height ceiling, for me sports hall would be ok with no heating 🙂. Best savings or could be switched off, again best savings, I am hard though.
    • CommentAuthorJeff B
    • CommentTimeNov 8th 2020
     
    I have never considered radiant heating. Is it any good? It's still electric at the end of the day so I assume quite expensive to use?
    • CommentAuthorSimonD
    • CommentTimeNov 9th 2020
     
    Posted By: Jeff BI have never considered radiant heating. Is it any good? It's still electric at the end of the day so I assume quite expensive to use?


    I installed an IR panel that looks just like a whiteboard in our temporary garden office. It's a 580W version I think. It's definitely more efficient than a fan heater or oil radiator, but I don't think I'd consider installing them throughout my home. The warmth feels lovely mind you as it's like having gentle sunshine on your back while working away. My wife loves it.

    I'm quite interested in the discussion on heat/light energy consumption as I'm also looking to design our lighting plan. I like the fact that LEDs save energy but I'm less enthused by their application. I don't generally like the quality of light emitted from them where with many versions I've experienced produce too much glare for my liking. Perhaps that's just down to poor specification and installation design patterns?
    • CommentAuthorJeff B
    • CommentTimeNov 9th 2020
     
    SimonD - thanks for your comments. Might try one in our conservatory!

    Re LEDs. I think it's a case of "horses for courses". We prefer the warm white versions in the living rooms/bedrooms but the cool white type in the kitchen, workshop etc where a brighter light is needed. I must admit I do tend to buy bulbs with a higher output than is probably necessary because the wattage is so low anyway!
    • CommentAuthortony
    • CommentTimeNov 9th 2020
     
    All direct electric heating is the same 100% efficient.

    Low temperature spectrum for me everywhere

    Should really calculate lumens, and beware of glare and over specifying how many needed - too common

    Don’t get me going on street lighting which will all have to get changed to very low temp spectrum 2400-3000K to protect wildlife eventually.
    • CommentAuthorSimon Still
    • CommentTimeNov 9th 2020 edited
     
    Posted By: SimonD
    I don't generally like the quality of light emitted from them where with many versions I've experienced produce too much glare for my liking. Perhaps that's just down to poor specification and installation design patterns?


    I think that's completely poor specification and installation design - most likely the terrible trend for electricians/builders/whoever to fit a huge number of fixed recessed spotlights in the ceiling.

    I bought a few books and read up before designing our lighting. We've got LED spots everywhere but they are all adjustable - the only ones that are set straight down are in the hall. If you use them to light the walls and bounce the light back into the room (light objects/artworks etc) the lights much more interesting and pleasant.

    You don't actually want/need many rooms super bright or evenly lit (except maybe when cleaning!).

    Led bulb replacements are really good now - Phillips the best I've found.
    All our lighting is 2700k colour temperature (except the workshop and utility room which have daylight fluro tubes)

    If I was doing it again I'd probably have slightly cooler light in the bathrooms and kitchen. The advice I've seen since is that you want a cooler temp (ie higher K number) where you're trying to supplement daylight rather than add mood when its dark
    • CommentAuthortony
    • CommentTimeNov 9th 2020
     
    +1
  14.  
    Simon: Can you share the books you read up on? Or can you give a bit more insight into light design?

    Eg. How many lumens per room/height of ceiling or m2 etc?

    We have led filaments on chandeliers in the hallway (2no x 5 bulbs) and I'd like spots, can you get chandeliers with spots? The missus is insistent on being chandeliers but lighting is an area of interest to me
    • CommentAuthorJeff B
    • CommentTimeNov 9th 2020
     
    I wonder how long it will be before the currently trendy recessed ceiling lights will be replaced with good old fashioned surface mounted ones. Lots of work for plasterers making good all the holes everywhere I suppose.
    • CommentAuthortony
    • CommentTimeNov 10th 2020
     
    just an unfortunate fad, pool at general lighting, a disaster for air tightness (even in g/f ceilings), I would love to see the back of them
    • CommentAuthorgoodevans
    • CommentTimeNov 14th 2020
     
    Posted By: Jeff BI have never considered radiant heating. Is it any good? It's still electric at the end of the day so I assume quite expensive to use?
    sorry, late to the discussion. All low temperature heating could be considered to be radiant heating - the lower the temperature diff to the room the less convection is a factor. Of course heating from above at almost any temperature is primarily radiant.

    Tony,
    We have installed recessed led lights throughout the house - mainly for their unobtrusive look (white bezel on a white ceiling) and our air tightness layer is well away from the plasterboard (at the rafter level) so not a problem for us. Being unfashionable I usually end up buying/choosing stuff just as it goes out of fashion - oh well.
  18.  
    Posted By: tonyjust an unfortunate fad, pool at general lighting, a disaster for air tightness (even in g/f ceilings), I would love to see the back of them


    I respectfully completely disagree. Airtightness shouldn't be at the plasterboard/internal ceiling level. The further out in the envelope the better. Recessed spots are a good way to light a room - way better than the classic UK solution of a single central ceiling rose which is utterly useless with a typical 2.4m ceiling when I'm 195cm tall...

    However, they need to be located with a bit of thought (not just a grid pointing straight down) and to be able to be directed. Wall mounted (or floor mounted) uplights good as well, some table lamps wired into 5A sockets linked to the room light switches too.

    In terms of design I bought https://www.amazon.co.uk/Lighting-Bible-Ideas-Every-Room/dp/1845433572 and it was pretty good.

    How many Lumens light you need is more difficult and I'm still not sure but if you're using bulbs that can be swapped out then it is something you can change fairly cheaply.

    (on the other hand I'm cursing the expensive wall mounted beside lights we bought. non replaceable LED with supposedly 60k hours life - even if they were on 4 hours a day that would be 40 years and the reality is nothing like that much. One now has an intermittent flicker. I'm guessing it's the driver thats' failed rather than the LED (anyone think differently?) so I *might* be able to source something of the right size to fit within the lamp case but I bet it's not going to be easy. For 99% of owners it would be in the bin.
    • CommentAuthorrevor
    • CommentTimeNov 15th 2020
     
    I went for Collingwood Halers have the transformers in each unit Collingwood did me a lighting plan for the whole house and apart from the landing illumination being too bright (will fit a dimmer) is spot on. Challenge was fitting them in the ceiling around trusses resilient bars etc. Have 7 year warranty (70000hrs life claimed) so in that time technology will have moved on but even so they can repair the unit if needed. There are many choices of colour temperature and we have mixed them e.g kitchen diner areas, warm over dining tables and cool over the cooking prep area and that works very well. They are all IP65 fire rated so no need to buy different sorts for different areas other than colour temperature and if you need tilt-able ones. They were well rated on the electrician forums.I do not know where they are made but Collingwood is a well known British company have excellent help lines. There are so many imported trash on the market I think it is worth the extra expense to get the best. Got the best price at local electrical national outlet cheaper than internet I found.
    •  
      CommentAuthordjh
    • CommentTimeNov 15th 2020
     
    Posted By: Simon StillAirtightness shouldn't be at the plasterboard/internal ceiling level.

    I think Tony was thinking of existing houses rather than the design of new ones where you have control. The space above the ceiling is very often a problem area.
    •  
      CommentAuthordjh
    • CommentTimeNov 15th 2020
     
    Posted By: revorCollingwood

    Reassuringly expensive :cool:

    I bought John Lewis cheapest own brand fittings. :bigsmile:
    • CommentAuthorCWatters
    • CommentTimeNov 17th 2020
     
    Posted By: VictorianecoSimon: Can you share the books you read up on? Or can you give a bit more insight into light design?

    Eg. How many lumens per room/height of ceiling or m2 etc?



    That depends on the room and its usage. If it helps there are comparisons such as..

    Lumens Incandescent light bulb (Fluorescent)
    375 lm 25 W (6.23 W)
    600 lm 40 W (10 W)
    900 lm 60 W (15 W)
    1125 lm 75 W (18.75 W)
    1500 lm 100 W (25 W)
    2250 lm 150 W (37.5 W)
    3000 lm 200 W (50 W)

    Some thoughts on spots/downlights..

    If you are looking at replacing existing downlights then be aware that a 50W 230V GU10 puts out less light than a 50W 12V MR16. I think in a kitchen they recommend a 0.9-1m spacing for 50W 230V GU10 and 1.2-1.3m spacing for 50W 12V MR16 (its a different spacing anyway).

    So with that in mind I reckon a 450 lumen LED is equivalent to a 50W 230V GU10 and I've made that swap. If you are replacing 50W 12V MR16 on the wider spacing I think you need to look for nearer 550 Lumen LED if you can get them. Elsewhere that comparison chart seems to work ok.


    The beam angle from downlight bulbs also varies. Personally on a grid like you have in a kitchen I prefer wide angle (120 degrees) over the more common 35 degree LEDs. You get a more even light with fewer shadows but a bit more glare. For some reason wider angle are harder to find.

    There is a vast array of LED "chandeliers" (aka ceiling lights) these days..
    https://www.google.com/search?q=modern+downlight+chandelier+LED&tbm=isch&ved=2ahUKEwiJmsSc3IntAhUC0xoKHd8uA0gQ2-cCegQIABAA&oq=modern+downlight+chandelier+LED&gs_lcp=CgNpbWcQA1CGkgJYzZsCYPmfAmgAcAB4AIABQ4gB8gGSAQE0mAEAoAEBqgELZ3dzLXdpei1pbWfAAQE&sclient=img&ei=6tSzX4n9BYKma9_djMAE&bih=833&biw=1461
    • CommentAuthorCWatters
    • CommentTimeNov 17th 2020 edited
     
    "CIBSE RECOMMENDED LIGHTING LEVELS"

    https://mountlighting.co.uk/technical/cibse-recommended-lighting-levels/

    1 LUX = 1 Lumen per square meter.

    Technically its not as simple as multiplying the required lux by the floor area because light gets reflected. Bulbs also don't emit light equally in all directions and other issues. However lets try that..

    The table says for a kitchen you need say 300 Lux. If your kitchen is say 4m * 4m that's 16sqm so you might need lights that generate 16 * 300 lux = 4,800 Lumens. That could be a 3 * 3 = 9 grid of downlights each would need to be 4800/9 = 533 Lumens.

    Earlier I said I was happy with LEDs around 450 Lumens so I guess this method may overestimate slightly.

    Apologies to any real lighting engineers.

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