We, as subservient members of the British Empire, love to quaff a cuppa at any time of the day with nary an excuse needed. Whether it be by mug, cup, infuser, or pot – we’re loving it. We’re saying pass the honey, honey. Pass the sugar, sugar. And pass the tea, bag. And getting slapped. But we still come back for more. But the big question is – what is the true cost of that boiled happiness?
The basic bits of calculator action are quite simple.
The only thing you really need to know is the heat capacity of the water you’re trying to boil. What this value gives you is the amount of energy needed to change the temperature of the water by 1 degree. This value is near as heck to 4.19. This value means that to increase the temperature of 1kg of water by 1 degree C we need to give it 4.19 kJ of energy.
So in real terms to boil 1 cup of water, which works out to be 250 ml or 0.25 litres, we first have to know the mass of the water. Luckily this is the same as the volume of the water – all because water is freakily ace!
We also have to know the starting and finishing temperatures of the water. We know that boiling water is 100 C. We’ll say the starting temperature of the water is 20. So to make the tea boil will take an increase of 80 C.
Now here comes the calculator bit. To heat 0.25 kg of water by 80 degrees – using a heat capacity value of 4.19 – we’ll need to pump in 84 kJ or 20 calories.
This doesn’t seem like much at all.
And for the pleasure of the Earl Grey it’s a small price to pay. But here’s the rub – and there’s always a rub. We never, ever, ever, boil just the cup. We all end up lazily filling up the kettle and pouring in it’s full capacity of 2 litres. That’s 8 cups worth. This means that we’re heating 8 cups for the sake of having 1. So what does the math look like now?
For 1 cup we found that we were chewing through 20 calories. So for 8 we’re smoking 160 calories. It gets even worse if you use filtered water from the fridge – the energy consumed is closer to 200 calories. With this kind of energy you could have played badminton for 30 minutes, croquet for an hour, or even walked to you local shop and bought an espresso, twice.
So the moral of the tale?
Take 2 seconds to see how much water you’re putting into your kettle. This energy is totally wasted and over a year you could have, at 2 cups per day, wasted 100000 calories (give or take). With that kind of energy you could have done that thing that you wanted to do last Tuesday week, at least twice!*
*Seriously, with 100000 calories you could have bird watched for 570 hours or even aerobics’ it up for 220 hours.