A week or so ago my other half proudly presented me with a new kettle. “Look!” she said “It’s an eco-friendly one!” And sure enough it was slathered in claims it would save 66% energy.
“Mmm”, I thought, putting on my electrical engineer’s hat (which is admittedly a bit dusty), “A heating element is 100% efficient, the heat capacity of water is constant, the heating time is so quick you won’t get significant losses through the sides, so what could possibly be 66% more efficient?”
The answer is, with a flat element and a gauge that lets you see if you have a single cup of water inside, you can save energy by only boiling the amount if water you need. When I explained this to her, she felt she had been conned. We ended up having a long conversation about greenwash.
Here’s the evidence as I see it:
For the prosecution:

• An intelligent, but busy person (she has a PhD and two small kids) assumed that the kettle itself was 66% more efficient, because she’s not enough of a green geek to pore over the details;
• The savings are almost entirely dependent on the user (and the user frequently making single cups of tea/coffee);
• The kettle hasn’t changed much – probably the most significant thing was the sticker on it about energy – now gone;
• As flat element kettles are getting more common, anyone could measure out a cup of water. Even with a traditional element kettle, you can use less water with a bit of care.

For the defence:

• The labels clearly said that the savings would be down to you being able to use less water;
• The nature of a kettle is such that the amount of water is the key factor in energy consumption;
• Philips are bringing the water factor to the attention of the user;
• The 66% figure came from a DEFRA study, so has third party validation.

So, you, the jury, what verdict would you give? Guilty, or not guilty?