Preheating the Oven: “The Recipe Says So” myth.

MattMattMattUK

t_squared said:

razord said:

Unless your oven takes an hour to heat up, it won't use 3kWh in an hour. It'll hit temperature after 10 minutes or so and then use a few watts until it needs to turn the heating elements back on. In my experience, my oven uses about 1kWh an hour.

The fact remains that energy is being wasted during the preheat period.

It is not wasted, you are failing to understand the cooking process requiring a particular starting temperature. 

MattMattMattUK

kingstreet said:

Pre-heat for five minutes or add five minutes to the cooking time.

Six of one, half dozen of the other...

That very much depends on the food being cooked, any bakery goods, pastry etc. will be substandard based on that way of cooking, fish will be less flakey, some cuts of meat may be nore chewed etc. it is really not that simple and also ignores the fact that depending on the temperature it may take more than five minutes to reach temperature. 

Apodemus

MattMattMattUK said:

t_squared said:

razord said:

Unless your oven takes an hour to heat up, it won't use 3kWh in an hour. It'll hit temperature after 10 minutes or so and then use a few watts until it needs to turn the heating elements back on. In my experience, my oven uses about 1kWh an hour.

The fact remains that energy is being wasted during the preheat period.

It is not wasted, you are failing to understand the cooking process requiring a particular starting temperature. 

The OP is also failing to understand basic microbiology! 

Marmaduke123

When I was working I often used to put a casserole in the oven on the timer. It obviously started off from cold, but was in the oven for long enough to get piping hot and fully cooked.  We never got food poisoning!

Longwalker

This is why Im now using my air fryer as much as possible. Cuts cooking time by at least 1/3 and doesn't need to be preheated

Floss

Longwalker said:

This is why Im now using my air fryer as much as possible. Cuts cooking time by at least 1/3 and doesn't need to be preheated

And the smaller size means less energy to get to temperature too.

Longwalker

Floss said:

Longwalker said:

This is why Im now using my air fryer as much as possible. Cuts cooking time by at least 1/3 and doesn't need to be preheated

And the smaller size means less energy to get to temperature too.

Precisely.

Yes it did cost to buy, but for everyday use Im saving money on electricity. Between it and the microwave I can cook a Sunday roast for pennies 

turnitround

In 50+ years of cooking/baking I have never ever pre heated my oven.  Probably shouldnt admit this either, I take no notice of instructions on packaging regarding timings. All my cooking from pies to a roast chicken dinner is pure guess work as regards timing. 
My sister on the other hand worried about all the timings and gets so stressed about what time the potatoes need to go in once the beef is cooking. 
I have never had food poisoning, nor have my guests or family.

Nymbus1

t_squared said:

In these days of astronomic rises in energy bills, I have an issue with pre-heating ovens.

I am appalled by the number of recipes and “how to cook” on bought food items that demand that you pre-heat the oven.

This is a complete and utter waste of energy.  Nothing is being cooked at this stage.

The average oven uses about 3,000 watts of electricity every hour (about 3 kilowatt hours).

Those 3,000 watts in one hour also emit as many emissions as burning 1kg of coal.

Common sense tells us that if we’re preheating the oven, that energy is just being wasted; it’s not cooking anything.

OK, some recipes do need a preheated oven, for example, baked goods with yeast.

But for basically everything else, preheating doesn’t really matter and remains a total waste of energy.

I have looked at this pre-heating issue online and time and time again, it is stated that pre-heating is, indeed, totally unnecessary

Up to 10% of the energy can be saved in the cooking/baking process.

Maybe a campaign to stop recipes and other cooking instructions to stop printing this unnecessary step.

A whole lot of expensive energy can be saved!

This is a good safety issue. 

As a food safety tutor and practitioner, preheating your oven ensures that food goes from the fridge to the oven at the correct temperature to destroy pathogens. This minimises the time in the danger zone 

in_my_wellies

I read years ago as a rule of thumb if the cooking time is less than 45 minutes then the oven must be pre-heated but if longer than 45 minutes then OK to pop it in cold. 

Makes sense for baked goods which rely on a shock of hot air to make them rise but for a roast chicken I still prefer to put it in a hot oven. My oven takes 8 minutes to get up to 160 fan so hardly a waste. And I always cook more than one item at a time.