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Revelations of a smart meter

Our so-called energy supplier was e-mailing its customers, asking if they were interested in having a smart meter fitted.


So I said, "Yes." (Somebody needed to.)


So now we have a smart meter.


It has been interesting to find out which appliances guzzle the most energy. It isn't lights. Not computers. Not even washing machines. Forget TVs on standby.


It's refrigerators.


We have a fridge-freezer and a separate larder-fridge. These have their ratings stamped on a metal label inside - 230 W and 90 W respectively.


The big revelation is the proportion of the time these fridges spend consuming that amount of power. In a hot summer's day they seem to be running almost continuously at that rate. On a cool autumn morning the consumption may be down to less than 100 W in total,  but open those fridge doors to grab something for breakfast and the power is soon rising.


Even the dishwasher and washing machine seem to compare favourably, consuming around 250 W most of the washing cycle. They peak into the kilowatts during heating phases but these last only a few minutes. And of course they do not run 24/7 like fridges.


These fridges are fairly old, and clearly I am considering their replacement, though they still work. Advice percolates in that newer fridges are much more economical on energy. I am willing to believe that is the case, but as an engineer I like things to be quantified. Most engineers are economists at heart and I should like to prepare a "business case" for replacement, and work out how long the saving in energy will take to pay for the replacement.


So how much power does a modern fridge-freezer consume?  I visited the web site of a well-known retailer of electrical appliances to see what I could find. Details were given of energy consumed in a year for various fridge-freezers, but no actual power rating. I went in-store to browse around. I peered at one fridge-freezer and opened a door, looking for a rating label but could not find one. A friendly assistant came up and asked if I needed any help. She suggested that I noted the catalogue number then went online and I should find the detail I sought. Back home I tried that but still could not find a power rating. I went to the websites of three different manufacturers of fridge-freezers. Again, all gave the vague estimate of energy used in a year but none gave a power rating.


I like to get down to fundamentals when I am evaluating. I sometimes wonder how these estimates of energy usage per year are arrived at. There must be many unknown factors affecting this, e.g. how warm is the room where the fridge is kept, how often is the door opened, what is stored inside, how damp, etc. I realise that even if I can find the power consumption of the motor when running there are still unknowns to consider, but at least I have something I can monitor fairly easily.


Typical figures I see quoted for energy are around 350 kWh per year. This is equivalent to an average power consumption of 40 W. Clearly my old fridge-freezer is consuming well over double this figure. The message is becoming clear, then, even if the analysis is blurred - I need to replace that fridge-freezer soon. It will probably save its cost in about four years.


I submit this post with an interest to find what others think about the way fridges are sold and how we are supposed to assess energy usage. Different manufacturers seem to present much the same marketing information. Does anyone know of any industry standard affecting the way this information is given?
  • Former Community Member
    0 Former Community Member
    You could start with a browse through IEC TC 59 and work "down" from there.


    Basically, for EU use, manufacturers adopt a standard test methodology so comparisons are equitable between brands and models - the so called "ISO" test methods


    They use an index that compares the appliance’s energy consumption with its internal volume, to show how energy efficient it is for its size.


    The appliance’s energy consumption is measured by testing it in a room with a temperature of 25˚ Celsius. The fridge or freezer is partly filled, and its internal volume is calculated once all its drawers, shelves, trays or water dispensers are in place. This isn’t necessarily the same as the volume claimed by the manufacturer, who may have measured it without all the drawers, shelves and so on - the test then is pretty standard to determine consumption under  that "norm"


    The novelty of the smart meter will wear off soon - so you should be able to get out more ?


    Buy a new fridge when the old one stops working


    Regards


    OMS
  • The other thing to consider is how the modern fridges/freezers achieve the improved efficiency, which is through better insulation. In part I think the newer insulation materials are more effective but they are also increased in thickness compared to older models. You will probably find that for the same (external) size of fridge or freezer you have less internal volume to store food (or whatever else you may want to store....).

    Alasdair
  • That is still only a few pence per day, so wait for it to fail.

    I have been holding off for aerogel insulation to become cheap enough for such products - for the same thermal impedance you need about half the thickness of it compared to polyurethane, and that in turn about half of fibreglass wool. We are not quite there yet, but it will be soon  I think.


    Also, site your fridge in a place where it can be easily cooled - it would be possible to make a fridge where the waste heat went to heat the washing up water, but as far as I know, no-one does, but at leat make it have an easy life.


    No free lunch, newer fridges, in a nod to the ozone layer problems, use different refrigerant gas fills to older ones,  and that tends to include hydrocarbons such as  pentane and other highly flammables (propane works well but is not so popular), and to get the same cooling, these have to be run at higher pressures than the older CFC types , so needing more pump effort  (and are more 'gurgly')

  • OMS:

    You could start with a browse through IEC TC 59 and work "down" from there.


    Basically, for EU use, manufacturers adopt a standard test methodology so comparisons are equitable between brands and models - the so called "ISO" test methods


    They use an index that compares the appliance’s energy consumption with its internal volume, to show how energy efficient it is for its size.


     




     

    Thanks, OMS, this is helpful information. I presume the energy labels one sees on new fridges are based on these tests. Standardised testing enables one to compare new fridges. The data are less precise for comparing with older models in use, but at least one can make some estimates.

  • Alasdair Anderson:

    The other thing to consider is how the modern fridges/freezers achieve the improved efficiency, which is through better insulation. In part I think the newer insulation materials are more effective but they are also increased in thickness compared to older models. You will probably find that for the same (external) size of fridge or freezer you have less internal volume to store food (or whatever else you may want to store....).

    Alasdair




     

    Yes, it is wise to check the internal dimensions of a refrigerator considered for purchase, because these are what count. For a larder-type fridge the external dimensions are critical in so far as it must fit under a work surface and within a space nominally 60 cm wide, so thicker insulation will reduce internal capacity, though there may be some flexibility with depth. Fridge freezers usually stand free in open space so external dimensions are less critical.

  • mapj1:

    . . .

    Also, site your fridge in a place where it can be easily cooled - it would be possible to make a fridge where the waste heat went to heat the washing up water, but as far as I know, no-one does, but at leat make it have an easy life.

    . . .

     




     

    Our fridges are in an unheated utility room, several degrees cooler than the kitchen in winter, so we are giving them an easy life as practicable.
  • Many years ago, we went on a winter holiday leaving the house central heating on a minimum setting to prevent freezing. On our return the freezer compartment of our Fridge-Freezer had defrosted.  A relative had a chest freezer in an unheated garage which never seemed to have that problem.  I came to the conclusion that my Fridge Freezer had been operating in conditions significantly below its recommended ambient temperature range. Has anyone considered this issue?

  • Former Community Member
    0 Former Community Member

    Denis McMahon:




    OMS:

    You could start with a browse through IEC TC 59 and work "down" from there.

    Basically, for EU use, manufacturers adopt a standard test methodology so comparisons are equitable between brands and models - the so called "ISO" test methods

    They use an index that compares the appliance’s energy consumption with its internal volume, to show how energy efficient it is for its size.




    Thanks, OMS, this is helpful information. I presume the energy labels one sees on new fridges are based on these tests. Standardised testing enables one to compare new fridges. The data are less precise for comparing with older models in use, but at least one can make some estimates.


    Yes, the labels are based on the standardized test so you can make sensible comparisons between brands, sizes etc


    Regards


    OMS

  • You will probably find that for the same (external) size of fridge or freezer you have less internal volume to store food (or whatever else you may want to store....)



    It just so happens that when my cat died, I think he must have had a heart attack as he appeared to be in full flight stretched right out laid up behind the curtain. I couldn't get to bury him so I stuck him in the bottom draw of the freezer for a week until I could find someone to stick him in the ground.

    Modern freezers do the job very well as he was rock hard when I retrieved him.....


    After all my continual opposition to smart meters my partner has signed us up to a fixed rate energy package which includes gas, electricity, broadband, mobile phone and a smart meter. I'll now be able to check my freezers for energy consumption...what fun!


    Legh
  • You are way behind the pack investigating the energy usage of your fridge and freezer. 


    For many years Savaplug made a control unit for fridges and freezer, but I think you roll only get some through EBay  now as they have been discontinued, though a Commercial version is available.


    Andy Betteridge