Is passive cooking better environmental choice?

OSO Admin October 6, 2022 0

Does Passive Cooking Use Less Energy?

Recently, someone asked me if passive cooking in the oven might be a good alternative to reduce energy usage. So, is passive cooking any better for the environment and If so, by how much?

The result is inconclusive! Ovens are off or on. The thermostat assesses the temperature and switches it off when it reaches the designated temperature, then back on when it falls below a threshold. The energy use will be dependent upon the oven.

So, if your oven is, for example a 2kWh model (most are between 2kWh and 5kWh).

If you set it to the highest temperature and then switch it off, you will use only that energy. So, let’s say it takes a 2.5kWh oven 5 minutes to reach 250°C, that will consume 208.3W (If your energy plan costs 44c per kWh as prices are now going, that will cost 9c)

If you set it to 180°C and leave it on for 10 minutes, It will likely not take as long to reach the temperature but since it is designed to continually switch on and off to maintain temperature for 10 minutes the probability is that more power will be used. It will depend upon the efficiency of the oven and therefore how many times during that 10 minutes the power must come on again.

What does make a difference is, when replacing your over, to opt for the highest energy rating possible because that will likely dramatically reduce the energy usage over time because it is more efficient at retaining heat.

One thing that might make a small difference to the above is the option to switch on the quick heat option on the oven. It will not increase the power usage, simply the number of elements used, although over time it may degrade the elements over time – see here

In conjunction with this, follow these guidelines whenever possible:

  • If you need to preheat the oven, put the food in as soon as it reaches the temperature required.
  • Keep the oven door closed during cooking to avoid heat loss.
  • Use as much of the oven as possible. If you can put a number of dishes in at a time, do that. Batch cooking is to be recommended for this reason.
  • Parboil vegetables to shorten the time they take to roast.
  • Turn off the oven 10 minutes before cooking time is finished and allow the residual heat to finish it off.
  • Portion your food into smaller pieces. 3 small hotpots will heat up quicker than 1 large.
  • Keep your over clean, particularly the elements.
  • Do your cooking outside of peak hours, for greater environmental benefit. In Ireland, between 4pm and 7pm are peak energy usage periods. Therefore, even if it’s a windy day and the majority of energy is created by wind energy, coal or gas generators will have to be used to meet the shortfall in generation based upon demand. If possible, arrange your meal so that you’re switching off the heat before this time and using residual temperature to finish it off, if possible.
  • If cooking something for short periods of time, use metal containers that heat up more quickly than ceramic.
  • Use your microwave. It’s more efficient than the oven.
  • Use a slow cooker which uses significantly less power over the same time period.

If you are going to try the passive option, you will need to consider the following:

  1. Don’t use the fan option on your oven to do this!
  2. If there is a cooling fan in the oven that switches on when heat is turned off (as many are designed to cool the oven down quickly after use), switch off the power at the mains switch.
  3. It will differ dependent upon the insulation, efficiency of the oven so it’s not an exact science.
  4. While there will likely be a difference it may not be significant from an energy usage perspective, if you’re talking about 10 minutes.

Every Little Thing Counts.

Citations and References

https://www.irishexaminer.com/property/homeandgardens/arid-40867118.html

https://www.electricireland.ie/news/article/how-to-become-an-energy-efficient-kitchen-hero#:~:text=The%20oven%20is%20one%20of,0.40)%20per%20hour%20of%20cooking

Fast preheat option on convection oven - does it use more electricity?
by inAskEngineers

https://cooking.stackexchange.com/questions/89600/energy-usage-of-an-ovenhttps://www.endesa.com/en/blogs/endesa-s-blog/tip/turning-off-oven-earlier

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