But biscuit energy is not in a form that we can easily use to run the equipment in our buildings. Our biscuits contain a certain amount of energy – 172 Calories or 0.2 kWh per biscuit. Probably the best option would be to eat the biscuit, but hopefully you get the general idea – the biscuit contains energy that can be converted into different forms.Įlectricity and other fuels supply energy in a form that we can use to run the equipment in our buildings. Some energy would be wasted in the conversion process, but it should be possible to get that burning biscuit to run a light bulb for at least a few seconds. Given the right equipment we could turn the heat energy from the burning biscuit into electrical energy to run lights and fans and so on. Or we could burn the biscuit and turn it into heat energy. We could eat the biscuit to provide us with energy. (That's with "172 Calories" meaning 172 kilocalories, which is the unit that is almost always meant when people talk about the "calories" in food.)Įnergy can change form. 172 Calories is equivalent to around 0.2 kWh. When people talk about a particular biscuit containing 172 Calories, they're talking about the amount of energy contained within that biscuit. Similarly, you can express a measure of energy in joules, or Calories, or kWh, or BTU etc. The distance between New York and London is fixed, but you can express that distance as 3,459 miles, or 5,567 km, or 18,265,315 feet etc. It's a bit like how you can measure distance in units of feet, metres, miles, km and so on. And these aren't the only units of energy – there's the BTU, the watt hour (Wh), the therm, and plenty of obscure units that you're unlikely to have heard of. The kilowatt hour (kWh) is a unit of energy. But fortunately we're not writing this for physicists.) (A physicist might throw their arms up in disgust at how we've over-simplified one of the fundamentals of the universe. Though it only seems simple after you understand it.Įnergy is a measure of how much fuel is contained within something, or used by something over a specific period of time. Well, the difference is really very simple. What is the difference between a kW and a kWh? Or, if you find it useful, you could buy or recommend our Energy Lens software – we really appreciate the customers that keep us in business.)Īnyway, that's more than enough preamble. (If at any point you'd like to thank us for our help in reducing headaches and embarrassment, please point your colleagues and website visitors towards this article so that it can help them too. Quite likely it will save you some embarrassment at some point too, as you'll be much less likely to make embarrassing calculation errors. If you're working with energy on a regular basis, and you don't fully understand the difference between a kW and a kWh, we promise you that taking 20 minutes or so to fully understand the concepts explained in this article will save you many headaches in the future. The name of this power unit is a tribute to the British engineer James Watt, for the recognition of the many researches that he made, to better understand the energy, as well as, the way in which he created machines that obtained a better use of it.Energy calculations, and energy saving, become much easier when you understand the difference between a kW and a kWh. To get an idea of how much Watt represents, here are some reference values of the power of some household appliances: stereo, 200 watts vacuum cleaner, 1000 watts computer, 400 watts exhaust fan, 300 watts electric oven, 5000 watts hair dryer, 1300 watts LCD television, 150 watts. This would be the same amount of energy that would make a 120-watt bulb shine for half an hour. For example, if a 60W lamp remains on for one hour, the power consumed is 60 watts-hour. To know the value of this, just look at your electricity bill, to see how much your energy provider charges you for kWh. As for consumption, this same air conditioner, if it was on for 10 hours would consume a total of 12 kWh. For example, the power of an air conditioner could be 1200 watts, or 1.2 kilowatts. Power is usually a constant value within a given circuit. This is because, the first is a unit of power, while the second is a unit of energy measurement. This may seem too technical, but it is especially important not to confuse kilowatt (kW) with kilowatt-hour (kWh). If we express watt in units used in electricity, we can say that a watt is the electric energy produced by a potential difference of 1 volt and an electric current of 1 amp. The Kilowatt is a power unit, equivalent to 1000 watts.
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