Should you get an electricity monitor to help reduce your bills?

I was on the radio this morning (BBC Radio Cambridgeshire) talking about electricity monitors and energy savings at home. I didn't have time to say everything I wanted to say, so here is a summary.

Most people who get an electricity monitor find they can reduce their energy use by 5-15%. I have posted on this subject before: Turning energy monitoring into energy savings - but that post is a bit old and things have changed a bit.

Types of meter

I strongly recommend that you get a plug-in energy monitor as well as a supply monitor. The plug-in works on a socket (as shown) and the supply monitor measures your whole house usage at the mains. The plug-in is good to check standby power for individual appliances accurately. Appliances bought since 2010 should use very little on standby becuase of EU regulations but older appliances might use up to 10W or more - which is another £12 on your annual bill for no good reason. The plug-in is also good with fridges and freezers, which turn themselves on and off on a thermostat - you can measure them for a day - and with washing machines and dishwashers which use different power at different phases - you can measure them for a full cycle.

There are two kinds of supply monitors now. The cheap and cheerful ones clip onto one of the leads going into your meter. They are not terribly accurate though they should be good to at least 10%. If you a have modern meter with an LED which blinks every Wh then you can use a monitor which watches it and counts the blinks. This is accurate but less responsive as it takes a while to count enough blinks to get a good reading. They may update only every half minute.

Where to get them.

The supply monitors are available from many places:

Your electricity supplier may offer them to you for free. For example British Gas has a scheme called EnergySmart. You get a monitor for free and it saves them money because they don't have to send a meter reader round any more; it gives them a reading every month.

You may be able to borrow one from your local library. You will only have it for a few weeks but this should be enough to tell you what you need to know. Of course if you fall in love with it you can buy one knowing it will be worth it. Some charities have them for loan too - for example Cambridge Carbon Footprint will lend you one for a few weeks.

You can buy one. The plug in monitors start at about £15 and a cheap and cheerful supply monitor will cost about £30.  If your electricity bill is £450 and you save 10% they will pay for themselves in one year. The basic supply monitor has just a sensor and a real time display you can have anywhere in the house. Many manufacturers - such as Efergy, Owl or Green Energy Options - offer more advanced systems which upload data to your computer or to a website. You can get a range of graphs showing your use over time. Also they can talk to smart plugs so you can switch things on and off remotely.

If you aren't sure about spending the money you can buy one and try it, then lend it to a neighbour or two and share the cost with them.

How to use an energy monitor

For the plug in meters, the first thing is to run around the house and measure how much everything takes on standby. Then you will know which things it is important to turn off and which things you don't have to worry about. If it is less than 1W it probably isn't worth a bust up with your partner/offspring about it - but if it is 5W then maybe it is.

Also, check how much your fridge/freezer takes each day. If this is much more than the energy label says it should it may have gone wrong. It will use a bit more in the summer so if you are measuring it in July/August don't get worried if it is 20% more than the label says. However, if it is using more it might need a new door seal or the heat exchanger may need cleaning,  or it may have a broken thermostat or worse. 

For the supply monitors, most people start by going round the house turning things off to see how much they use. Remember the clip on ones won't be exactly accurate to less than about 50W and things like fridges and freezers will turn themselves on and off so this will affect what you see on the monitor. However you can turn them off for a while without the contents warming up as long as you keep the door closed.

After that you need to put the display in a convenient place where you will see it often. Get to know how much you normally use and how much it goes up when you turn things on like the TV, computer, games and so on. Many people find it helpful to keep it by the door and check it before leaving the house. If it is high then something is on that should not be.

Also, supply monitors record your use over time and tell you how much you use each day or week. This means you can check if it is unusually high and investigate why and you can set yourself targets to reduce consumption.

Where to make savings

The monitor doesn't save anything by itself but it makes it easier for you to see where you are using most energy. The things you need to do, you know anyway but the monitor helps to remind you. Here are some good ways to save electricity, in no particular order:

• Dry your washing outside instead of in a tumble dryer - sunshine is free (when it shines).
• For your washing machine and dishwasher, especially the dishwasher, don't run them more often than you need, wait until you have a good load, and run at a lower temperature if possible.
• Fit energy saving light bulbs
• Turn off appliances which you aren't using especially old ones which can use a high standby current.
• Turn the TV off if you aren't watching it. Maybe try turning the brightness down as most of the energy goes into the display.
• Make sure you enable power saving mode on your computer and monitor.
• Consider energy efficiency when buying a new appliances, and  remember that a large A rated appliance can use more than a smaller one with a B or C rating. This applies especially to TVs, fridges and freezers.
• Set top boxes for your TV can use up to 20 W or more. Sky boxes have a power saving mode which uses only 0.5 W but you have to enable it explicitly.
• Don't overfill your kettle - heat only as much water as you need.
• If you have an electric shower, don't linger in there longer than necessary as they use 7-10 kW or even more. At 10 kW, one minute less in the shower every day saves you £9 per year.

It can be hard to keep track of how much each appliance uses and see where you can make the most savings. Tools like my energy use calculator can help you visualise where it is all going.

Switching suppliers

You may be able to save money by switching suppliers, though the one that is cheapest this week won't necessarily be cheapest next week. You can consider switching to a co-op supplier - so you get a share of their profits. Also you may find a community scheme whereby you join a group of households who all switch together - the group can negotiate a better deal than individual households. This is a very new idea and Plymouth Community Energy is one of the first. I am not sure if you have to live in Plymouth to join.