Green your home: The kitchen

From boiler to kettle to hob, the kitchen is full of energy-guzzling appliances. A monitor will help you keep track

Condensing gas boilers

What are they?

Condensing gas boilers periodically condense and extract heat from the exhaust gases that would otherwise escape through the flue – making them significantly more efficient than the conventional boilers found in most homes. There are two types of condensing boiler: regular and combination. Regular ones heat your hot water through a hot water cylinder; combination ones give instant hot water without the need for a cylinder. Either can be fitted to an existing central heating system.

How much do they cost?

Changing a boiler is not cheap. While there is help for households on certain benefits (see Warm Front ), you will not get much change out of £2,000-£2,500. In many big houses, it is more likely to be £3,500 once a new set of heating controls, installation and the odd radiator are factored in.

Are they worth it?

Around 60% of CO2 emissions from your home are down to your boiler, but unless you need a new one, probably not. Given that they don't last as long as they used to, there seems little point in ripping out a perfectly good one. The Energy Saving Trust claims that someone replacing a 10- to 15-year-old model would save around a third on heating bills – that is, up to 875kg of CO2 and £170 a year. However, these estimates look a little extravagant – most engineers will say you'll be more likely to see a 15%-20% reduction in gas consumption, which will equate to a £100 typical saving in lower annual gas bills.

Home energy monitor

What is it?

If you had a digital display in your kitchen showing your electricity consumption in real time, would you be more likely to turn off unnecessary lights? The answer, according to most trials, is an unequivocal yes. If your household is always leaving lights on, you need an energy-saving monitor.

They are easy to install – simply apply a clamp to the wires at your meter, which sends a signal on usage to your monitor. Within a few minutes, your actual consumption is displayed on the LCD screen which you can put in any room you like.

They are quite sophisticated and will show you your consumption in watts, as well as in monetary terms. Go round the house turning off lights, or switching other items off "standby" and note how much you are saving. You can also compare usage over the previous periods and different TVs or fridges to see which consume the most power.

How much does it cost?

Over the last 12 months, the cost of energy monitors has come down substantially. The Owl monitor, which used to cost £50, is now £35 (at The £44 Efergy Elite Wireless Energy Monitor (from the same place) is better. Turn on your kettle and the consumption jumps alarmingly; turn things off and it notes the reduction (and cost) almost immediately. The makers say that once you've got one you'll become passionate about reducing consumption.

Is it worth it?

Oh yes – reducing the amount of electricity you consume is one of the easiest and greenest money-saving things you can do. And, believe it or not, households that have installed one have seen their electricity consumption drop by as much as a quarter – saving, in some cases, up to £100, and a whole load of C02. Most people will easily save the unit's cost and bigger households will do so several times over. Children can be given financial incentives to make sure lights are always off. Time to get monitoring.

Recycling grey water

What is it?

Grey water is simply the water used in washing dishes, clothes and showering that is allowed to cool, then saved from going down the plug hole and redirected to the garden – either by bucket, or specially installed outlet pipes. More advanced grey water recycling systems redirect old bath and washing machine water to supply toilet flushes. Reusing grey water could save 18,000 litres per person a year, or a third of daily household water use.

How much does it cost?

Very little if all you are doing is using a bucket or an outlet pipe from the kitchen/bathroom. A recycling system for toilets such as the German-made Pontos AquaCycle system adds around £400-£600 to the building costs of a family home. Fitting it into an existing home is ­prohibitively expensive.

Is it worth it?

The average UK household water bill is £342 per annum, so a recycling system that saves up to a third of your water will take a long time to pay off. If your water is not metered, there are no savings at all.

The Centre for Alternative Technology has reservations about reusing grey water.

It says: "If you want to reuse grey water from a washing machine on the garden, try to use detergent that is low in sodium, as [otherwise] it can damage plants and degrade soil. Ex-kitchen water can be very dirty, and contain undesirable things like grease, oil, and chemicals … it's best not to reuse it.

"Research into the impact of systems that treat grey water for reuse in the home have shown that the environmental impact of such systems (using chemicals and/or energy) usually far outweighs the benefits. It's always best to first reduce the amount of grey water you produce."

Think Again

Kitchen appliances

From basics like the oven, kettle, fridge and washing machine, to extras like a dishwasher, microwave and juicer, the appliances in your kitchen are big energy eaters. But you can take steps to reduce your consumption and bills.

Top tips include:

Only boil as much water as you need in a kettle

Only use a freezer if you store enough food to fill it – half-empty freezers cost more to run than full ones

Use the right-sized pan for the hob and use a lid when boiling water

Washing clothes at 30C uses up to 40% less energy than higher temperatures

Microwaves are more energy-efficient than ovens

The most energy-efficient clothes dryer is a washing line

If you need to replace an appliance, go for an energy-efficient model. Look for the Energy Saving Recommended logo, which guarantees that the product is the most energy-efficient in its category, will cost less to run and help lower CO2 emissions. You can find ESR products here.

Even if you've got an old appliance that's still going strong, it may be more energy- and cost-efficient to replace it, according to the Energy Saving Trust – if your appliance is 10 years old or more, then it will save CO2 and running costs.

For example, replacing an old fridge-freezer with a new ESR model will save around £39 and 140kg of CO2 a year.

You can buy A+ recommended fridge-freezers from as little as £250, so it pays to be energy-efficient.

But on washing machines, the savings are less. Switching to an ESR washing machine could cut your energy consumption by up to a third compared to an old washing machine.

But the saving in electricity is only around £11 a year, so on financial grounds there's not much to recommend it.