One single unit of measurement — kilowatt-hours — can tell us all we need to know about energy consumption and our efforts to save the planet, according to David MacKay, a physics professor at the University of Cambridge.

Writing for the BBC News, MacKay explores the kilowatt-hour impact of everything from taking a hot bath to driving an electric car. Among his findings:

• Turning off phone chargers when not in use to save energy is “like bailing the Titanic with a teaspoon”;
• Adjusting your thermostat, on the other hand, is one of the most effective energy-saving strategies Britons can take;
• Hydrogen-powered vehicles are an “energy disaster” in terms of kilowatt-hours, actually using more energy than an old-fashioned petrol-powered car;
• Electric cars, though, are more efficient than standard vehicles and could have a huge impact on the UK’s energy footprint if the nation makes the switch to greener sources of electricity;
• Heat pumps are far more promising an energy saver than combined heat and power plants, while small rooftop wind turbines on homes are “an utter waste of resources.”

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