I’m not convinced that I’ll participate in Earth Hour. Don’t get me wrong, I think it’s a terrific idea for raising awareness of climate change and energy issues. But I’m already well aware of those issues, thanks, and I’m working on reducing my emissions every day, not just one hour per year.

And besides, I’m enjoying watching Big Love (and, I’ll admit, Top Gear — Jeremy Clarkson may be an idiot, but he’s a very entertaining idiot) on a Saturday night, and I don’t particularly want to sit in the dark.

The saving in emissions is said to be 5% if you switch off the lights for an hour. But lighting only accounts for 3% of the average household’s emissions. Let’s see that graph again:

Another way of putting it is this: if you save 1kWh of electricity by switching off for an hour (which might be 8 x 100watt lights if you’re still using the old ones and you normally leave ten of them blazing) and a big television, you’ve saved about 1kg of CO2. But the average car will generate that in travelling less than 4 kilometres.

Which means when last weekend I twice travelled by bus to Monash Medical Centre and back (about 7.5km each way, so 30km in total), I actually saved 7.5 times the equivalent of turning off the power for an hour.

I also saved money; it costs $6+ to park there, though now I come to think of it, I spent some money on bus tickets and a snack in the hospital cafeteria. Still ahead overall though, even before taking petrol into account. The problem is I had to put up with 40 minute bus services to do it… which of course is why more people don’t do it.

Businesses participating will make more of a difference. The Age reports: At David Jones, non-essential lights and electrical equipment in 35 stores, offices and warehouses will be switched off. Staff are being asked to ensure all computers and lights in their work space are turned off..

But hold on. This is 8pm on a Saturday, when David Jones stores would be closed. Isn’t all this stuff they should be doing anyway, every night when they’re closed? With the exception of emergency lighting, refrigeration for food, and arguably advertising/shop window displays, at that time of night they should be using hardly any power anyway.

These days, all workplaces should automatically shut off power outside working hours (with overrides if people are working late), including putting computers to sleep if possible.

So anyway, Earth Hour itself will barely make a difference to emissions, especially for households. But in terms of raising awareness, hopefully it makes some impact, and people get better at conserving energy right through the year, not just for an hour.

PS. 10pm.