Consuming Issues: How to save £600 on gas and electricity

September's sun is a memory and nights are darkening. Households are starting to feel the chill, not only from the cold, but the failure of Britain's big energy suppliers to lower prices. Consumer groups, MPs, the regulator Ofgem, seemingly everyone apart from Energy Secretary Ed Miliband has noticed that what went up last year, our bills, have not come down, despite drastic falls in wholesale prices.

Indeed, last month the Big Six – British Gas, EDF, E.ON, Npower, Scottish Power and Scottish & Southern – brazenly stated they had no intention of dropping prices this winter. An exasperated Ofgem admitted it had no power to bring about lower bills.

You, however, do. By switching supplier and saving energy, you can easily knock £600 off your bill. Of course, you may already be on the very cheapest tariff and have installed all the latest energy saving techniques, in which case, stop reading now.

First, switching supply. The average annual combined fuel bills paid by cheque quarterly are £1,239, according to Consumer Focus, the publicly-funded consumer champion. However, because two new independent suppliers have introduced cut-price deals in the past month, 99 per cent of households are paying too much. First Utility's internet i-Save works out at an average £954. Ovo Energy, which sources 15 per cent from renewable supplies, costs £978 a year.

You don't have to change any pipes, the electricity and gas coming into your house will be the same. All you have to do is go to a price comparison sites such as theenergyshop.com, energyhelpline.com or uswitch.com, enter your postcode, search for the best deal and switch. It takes about two minutes. It may be the easiest £285 you make; you've saved 23 per cent of your fuel bill. Now to the rest.

Energy saving is boring, but one of its virtues is that once you've made the changes, you don't have to do them again.

First, free things you can do immediately. One very effective way of cutting bills is to heed the hoary advice of putting on an extra jumper and wearing pyjamas in bed. Why not keep the central heating off until November? That's worth £60.

Turning down the central heating thermostat by one degree saves an extraordinary amount, £55 a year; it's unlikely you'll notice the difference (especially wearing that chunky-knit Aran jumper). Here's a similar one; don't heat your water so much. If you have an eco setting, choose this, because your water will then be heated on demand rather than in advance, just in case. If your water is ever uncomfortable to touch, lower the thermostat, which should work out at another £50.

You've now saved £450.

Now to things that cost some money upfront, but pay back quickly, usually in a year or two.

Why pay for your TVs, DVD players and computer when you're not using them? On standby they can clock up three-quarters of their "on" energy use. A Bye Bye Standy kit will switch them off at a click button at night or during holidays, saving an estimated £38.

Now to insulation and draught proofing. If you haven't had insulation fitted to your roof in the past 10 years, you've almost certainly got too little. Mineral wool insulation should be 270mm. Topping it up to that level is an easy DIY job. It might cost £250 upfront, but saves £45 a year.

Filling gaps between skirting boards and the floor saves £20. A jacket for a hot water tank saves £35 and an eco-showerhead £25 a year.

Now to energy saving lightbulbs. You may have installed a few already. But now there's an eco lightbulb for every socket: table lamp, dimmer switches, even the halogen spotlights that power down from kitchen ceilings. Wilkinsons even sells a one-watt LED light – one fiftieth of a typical 50w halogen, though it has a rather white light.

Replacing all the remaining traditional bulbs in your home with energy saving light bulbs saves £37 a year.

All these measures are highly practical. You could do most of them this weekend. And, notwithstanding some upfront costs, they would slash your fuel bill by £650. Year after year.

Heroes & Villains

Hero: Subway, the US chain, has cut salt in its Sub sandwiches by almost a fifth. The amount of salt, for example, in a six-inch Turkey Breast and Ham Sub has fallen by 26 per cent, from 3.4g to 2.5g, while a six-inch Ham Sub is down from 3.1g to 2.3g.

The recommended daily maximum for salt is 6g per adult. So beware, a Meatball Marinara still weighs in at an unhealthy 3.7g. But still, Subway is moving in a healthier direction...

Villain: Mercedes misled the public by making dubious environmental claims in its advertising for the new E-Class (left). Although the car pictured had emissions of 139 grams per kilometre, 22 of 24 models in the range emitted more pollution. Some of them, the Advertising Standards Authority pointed out, were rated M in the Government's VED emissions rating, making them the most climate unfriendly cars on the road. Mercedes told magazine readers: "It's a pleasure, but not a guilty one."