With or without lid has little meaning.
You are probably thinking that water boiling is the easiest thing in the world? That’s probably the case, and you may have heard that the water boils faster if you have lured the saucepan. But do you know how much energy you save by luring?
How to cook water
Basically, water boils because the molecules in the water are set in motion by the supplied heat energy, which in turn creates gas bubbles. When the pressure in these bubbles becomes large enough, they will rise through the water and break the surface and we experience it as the water boils.
The boiling point of the water is 100 degrees at 1 atmospheric pressure, but at lower pressures the water will boil at a lower temperature, simply because the bubbles face less resistance when they break the surface. At a higher air pressure, the temperature increases when the water boils.
At the same time, the cooking time of water is affected by the temperature around the water, including the temperature of the air above the water in the saucepan.
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We have made a simple kitchen experiment, without guaranteeing scientific reliability, but the experiment nevertheless suggests that there is little difference in cooking time, and this means little to spare on the lid.
But although there is not much to save on cooking with lid, there is still a lot to gain from being conscious of their energy consumption.
– There are many measures that do not cost anything that can be implemented and which can lower energy costs by 10 to 15 percent, “says Enova Svarer, Trond Paasche, Energy Counters.. no.
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– And if you also install power management systems, savings can be up to 25 percent.
According to Statistics Norway (SSB), the consumption of Norwegian households in 2009 was 20 400 kWh and a downward trend. Furthermore, the electricity price was 1. quarter according to Statistics Norway 88.6 øre / kWh. Therefore, if we assume a yearly consumption of 20,000 kWh, it will save a saving of 1700 to 2600 kroner annually just by becoming more aware.
In addition, if you install power management, savings can be up to NOK 4400 per year.
Therefore, it takes longer to cook water without lid
– When boiling water without lid, the air above the water will be in circulation, and since the temperature of this air will be lower than in the water, it means that this air “steals” heat from the water, and so the cooking time is extended, “explains Professor in physics at NTNU, Alex Hansen, to click. no.
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– But when the lid is on, this leak reduces heat from the water, which means it will take less time to make it boil, he expands.
However, which will pull the cooking time the other way, is the fact that the lid will cause a slight pressure increase inside the saucepan.
– But this is so minimal that I do not think it will affect the cooking time, “says Hansen.
The temperature of the water will, however, be the same because what we experience as cooking strictly is only gas bubbles that leave the water.
15 seconds longer cooking time
Click. No has done a simple attempt to see how longer it took to cook water without lid.
We filled a boiler with one and three liters of water, which kept around 20 degrees. The boiler was cooled between each boiling.
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Furthermore, the boiler was put on an induction stop with circular cooking areas. Maximum power in the used area was 1.8 kW and the boiler filled the entire circle. The boiling area was cooled between each boiling until the sign of excess heat went off.
We turned the power up to max and set the timer to start as soon as the power was max.
We measured the temperature with a digital thermometer with a probe plunged into the water.
For different reasons, it was not possible to start and quit cooking at exactly the same temperature, therefore a reference range for the temperature was established based on the first boiling attempt. There we had a starting temperature of 21.4 and a finishing temperature of 98.7 degrees. The difference of 77.3 was used as a reference interval. The deviation from this range was used to adjust the actual cooking time for the three other boils. The actual cooking time was calculated using the following function: Measured cooking time – ((4.18 kWs / K * Kg) * dT * m) / 1.8kW). dT represents the deviation (measured in Kelvin (K)) from the reference range of 77.3 degrees, while m is the weight of the water (1 and 3 kg respectively).
The following actual cooking times were measured:
1 liter of water
3 liters of water
With all possible reservations about deviating reliability for the experiment, the test indicates that the difference with and without lid is small. Calculated in kWh consumption, there is a difference of 0.0075 kWh and 0.0055 kWh respectively.
Trond Paasche explains the small deviations with the induction peak’s high efficiency, which makes the cookware warm quickly.
– But induction peaks are hardly the ones that are most common in homes, he explains.
Professor Hansen elaborates on this:
– The heat flow from the water to the air is small. If the heat flow from the plate to the water is much greater than this, the air will relatively have little cooling effect in relation to the heating effect from the plate.
But even though boiling with lid does not give the big energy gain, according to Paasche, many energy assets in the home are easy and free of charge can get rid of. The result may be more good restaurant visits as a bonus.
Doing nothing but getting more aware can save a couple of thousand flaps.
– It’s about turning off the light when leaving a room and replacing the bulbs with LED bulbs, says Trond Paasche.
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– And the new LED bulbs no longer have this cold light, but a hot one.
Another point he draws is the use of a dishwasher. Many people owe, for example, cups and vessels with hot water before putting it into the machine.
– There is no intention of rinsing with hot water, using cold water or scrapping of the foodstuffs, points out Paasche, which also draws the dishes of pots.
– There is no doubt that you use more energy by washing them by hand. Place the dishes in the dishwasher.
Easter emphasizes that it is also important to wash with a full machine.
Electronics Steals Energy
Most of us have a lot of consumer electronics standing around in the home. According to Paasche, in particular, old models steal a lot of energy.
– Measurements have been made on old game consoles, and it turned out that during a year they were 1000 kWh when they were not turned off after use. Old desktops also use a lot more than portable. Generally, newer consumer electronics have a lower consumption than their predecessors, and it indicates that manufacturers have followed up the market’s demand for more energy-intensive products.
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