Mini Oven

  • wizzo227's Avatar
    Level 21
    Does anyone else have experience of "mini oven" kitchen appliances and things like that to cook with less energy than the full sized oven ? Can we get together some comparison figures and metered test examples so that readers will know what to buy ? What else do people cook with for lower bills than traditional ?

    My best saver is to have solar photovoltaics on the roof and to preferentially wait for sunny times to cook with mainly locally generated renewable power.
    Last edited by Han_EONNext; 13-03-23 at 17:08.
  • 22 Replies

  • meldrewreborn's Avatar
    Level 91

    I've heard good and bad reports of Air fryers.

    Personally we've always cooked with gas and our current hob and oven/grill are 35 years old and going strong. The capital cost of fitting something new would have to be set against the running cost savings, and @retrotecchie did do some calculation on electric cooking costs a while back.

    It gets complex because the "waste " heat from cooking goes into the home so in a way supplements home heating half the year when the heating is on. So cooking is virtually free while the home is being heated. Saving from any new appliance would need to be considerable if payback is for only half a year's worth of use.

    The same consideration applies to your dehumidifier proposition. All heat pumps inside the home (fridges/freezers, some tumble dryers and dehumidifiers) use electrical power and their motors will give off an equivalent amount of heat to their consumption. In the winter that will be displacing the need for that amount of heat from another energy source. My home heating is from Gas, which is much cheaper than electricity so its still worthwhile limiting the electrical use and use the CH instead in the winter.
    Current Eon Next customer, ex EDF, Zog and Symbio. Don't think dual fuel saves money and don't like smart meters. Chronologically Gifted. If I offend let me know by private message, but I’ll continue to express my opinions nonetheless.
  • meldrewreborn's Avatar
    Level 91
    @retrotecchie posted this

    But he also posted an essay on alternative approaches to cooking a meal with costings but I can't find it.
  • wizzo227's Avatar
    Level 21
    Test Case 23-Feb-23 Two Slices of Cheese On Toast,
    cooked in the grill of the main oven
    used about 0.9 kWh ( 30p at Winter 2023 price electricity )

    what would you do to score better kWh when cooking ?
  • JohnT's Avatar
    Level 10
    Forget air fryers. I love my halogen oven.
    It's 12 litre and 1300w and cost me less than £40 from Amazon two years ago and still going strong.
    It's a glass bowl with the heating element and fan in the lid, so really it is a fan oven that you can see into.
    It plugs into a mains socket on the the kitchen worktop and has a temperature and timer control.
    My calculations show it cooks at about 1p per minute at 200C on my current tariff so about half the cost of using my main (electric non-fan) oven, and no need to warm it up first!
    Last edited by JohnT; 24-02-23 at 09:49.
  • wizzo227's Avatar
    Level 21
    Sounds like you found a better thing than my even cheaper even smaller mini-oven from Belaco, which I'll get to eventually.

    Test meal 24-Feb-23 One generous plate of spagetti with beef bolognese
    Today I used two gas rings on the stove to cook up 110g (dry weight) of spagetti and to reheat 200g of bolognese mix (from previous batch cooking).
    Reading the plain old gas meter (in metres ^3) before and after, and converting to kWh by the same ratio as my gas bills (multiply by about 11.13), reheat bolognese used about 0.52 kWh of gas today.

    We are still in the winter heating season so much of the heat which went into cooking would, today, have otherwise been wanted for the gas combi boiler towards heating the house.
    The sun has just come out (for the first time today), so the heat pump goes on downstairs using solar photovoltaic surplus. Having been somewhere else all morning, the living room was 16C just now.
    Last edited by wizzo227; 25-02-23 at 11:24. Reason: gas "today" does not include that used in batch cooking, nor freezing, and nor does it include CO2e of making and transporting the ingredients; mainly the beef. revised kWh/m^3 gas calibrati
  • wizzo227's Avatar
    Level 21
    Test meal 26-Feb-23 One generous plate of spagetti with beef bolognese
    Exactly the same meal as 24th, this time cooked on one electric hob ring with mainly rooftop solar power.

    Pre-warmed water from the small kettle was used with exactly the same 110g dry weight of pasta as previously.
    The plug-in energy monitor showed 0.295 kWh of electricity used in cooking. Pans were stacked so that steam above the pasta warmed the frying pan of reheat bolognese, which warmed an upside down plate instead of lids.

    This time I also noted 0.2 kWh of electricity used in the small kettle to do the washing up and have a coffee after. With the small kettle being inside my solar generating capacity, that could also be done for free, in the summer. Sadly not today. With partly cloudy (3/8 cumulus) weather, we get unpredictable minutes of up to 2kW of generation and then too little to use for cooking, even with this smallish 1.2kW electric hob.

    So, for todays' meal, I'll claim "0.5 kWh". It is important and unknown whether this used "half solar", in which case gas would be cheaper, or "three quarters solar", in which case electric was definitely cheaper. Electric just about wins on CO2e irrespective of whether it was half or three quarters solar, with the biggest uncertainty (see )for my region at present being 40% of national grid electricity being "imports", for which CO2 does not get counted.

    I'm not about to tell everyone to buy an electric hob like mine, which I got for £5 from a second hand shop, because it has a truly horrible thermostat. There is design fault / (cost reduction feature) placing the thermostat more in contact with the outer steel housing than with the hot ring, making it unsuitable for unattended cooking.
    Last edited by wizzo227; 27-02-23 at 14:48. Reason: shortened
  • wizzo227's Avatar
    Level 21
    Test Meal 28-Feb-2023 a hot drink and Toast
    Using the plug-in energy monitor.
    Small kettle to do one mug hot drink 0.063 kWh
    Toaster, two slices of white bread toast 0.024 kWh
    Small kettle to wash up and a second hot drink 0.096 kWh
  • meldrewreborn's Avatar
    Level 91

    i only have a similar plug in meter- no smart meter. You I think have both. Which do you think is the most useful in energy saving research?
  • wizzo227's Avatar
    Level 21
    Without a doubt, the plug in energy monitor is more useful to me to find out what is using the kWh in the home and to test suspect old or miss-sized appliances for efficiency.

    No smart meter, and for a reason. Any typical household activity, such as running a toaster for breakfast, Never fits neatly into half-hour timeslots as used by SMETS2 48 interval per day meters (I refuse to call those things 'smart' even when everyone else does, because its only intelligent features are the tamper-proof lid and the comms encryption to report back to The Evil Billing Supercomputer in Coventry or wherever it is.)

    The other thing which I use (and if you already have a smart meter in-home-display those might be better. Anyone got a comparison test?) is a wireless home energy monitor from Efergy. A current-clamp around N at the meter tails and wireless wifi to the LCD display unit on the coffee table (or picked up and carried around) shows net kW in or out of the whole house. That is less good than the smart meter version because it only displays ("kW") from presumed 0.24 rms kV x rms Amps, which is a few percent up and down during the day as line Voltage varies from 0.23 to 0.25 kV rms and is only strictly true for the plain sum of plain resistive loads such as kettles, toasters, heaters, and the perfect part of the rooftop photovoltaic generation, which is most of it.

    For example this lunch time, with the Efergy 0.24x I(rms) displaying "0.6 kW", did that mean generating, or consuming ? The only way to tell for sure is to switch on a kettle. This time it went to "1.4 kW" on switching on a 0.9kW kettle, showing that it had been 0.6kW mostly-consuming. That was how I decided to switch off the 0.7kW(electrical) heat pump on this gloomy afternoon. The Efergy then showed less than "0.3kW" which is down into the untidy bits of Current waveform from computers and so on minus rooftop generation, so neither generating nor consuming and to be ignored.

    I use the Efergy daily to decide Y/N switch on the heat pump then Y/N switch on another electric heater in really sunny cold weather. It is my first indication that the solar panels are generating enough right this minute.

    Cost comparison:
    SMETS2 meter : >£300 per household taken from £11BN long term mandated funding costs added to everyones' bills
    Efergy : about £40
    Plug in energy monitor : less than £25

    If I could opt out of paying for everyone elses' SMETS2 meters from not having one myself, that would save me £300 plus interest over the duration of the long term mandate.