Towns and cities around the world are turning out the lights for an hour to highlight the threat of climate change.

Sydney was the first major city to begin “Earth Hour”, when at 2000 (0900 GMT), lights went out on landmarks like the Opera House and Harbour Bridge.

Lights were then turned off in Bangkok, Manila, Budapest, Copenhagen and Dublin as those cities joined the effort.

I can’t really see the point in this exercise. The majority of architectural and shop lighting is discharge lighting, which when turned on has an initial surge that is far greater than it’s running current. This alone, across the amount of lights that were turned off, would probably still use up a good proportion of the power they would use with the lights still on.

I personally think all architectural lighting should be switched off at around midnight - 2am. Whenever I’m working late in London, I’m always surprised by how much lighting is still on when no one is around. I appreciate that London is a huge tourist attraction and certain areas can look good at night when lit. But how many tourists realistically walk around London after 2am?

If you really want to make a dent in the power consumption market and prove that you’re green, turn your buildings lights off for more than an hour.