NW_HOT_WATER

It takes a lot of energy to heat up water and even more to evaporate it, whether deliberately or incidentally. If we include cooking, which not only uses hot water to perform many things, but always involves reacting the water inside the food water heating is the second largest use of energy in the home after space heating. There are definite opportunities to make substantial savings here.

How to heat water If replacing a central heating boiler today a high efficiency combi boiler is usually recommended as being the most efficient. This may be true in a new house, where the boiler can be located close to the main taps to minimise the length of hot water pipes. In an existing house the new boiler will often need to be sited some way from where the original was and usually involves long lengths of pipes that end up full of hot water left to cool down.

Providing the pipe work between new boiler and hot water cylinder (in the airing cupboard) is well insulated and the cylinder itself is also well insulated (the single most cost effective energy efficiency measure), then a conventional is just as good as a combi. It is also easier, later, to add a solar hot water panel if the hot water cylinder is retained.

Using less hot water is an obvious step to take, especially if you are on a water meter. Getting into the habit of putting a plug into the plug hole is one good way. Using a dishwasher is another way to use less water (and uses less energy than washing dished by hand.) If you are in the habit of taking a bath rather than showering, consider how much water you really need.

Showers have a reputation as a way to use less energy. While this is true it is not as straightforward as it might seem. Early showers were low powered, using small amounts of electricity but also running quite cool with quite small flows of water. No wonder we stay under for too long. Modern showers are much more powerful, producing large amounts of hot water, so the amount of hot water used is much more.

Add to this the convenience. We wouldn?t think of having a bath every morning when we get up. When teen age boys finally discover the opposite sex their personal hygiene undergoes a transformation with a huge increase in the use of the shower. If you are unfortunate enough to have offspring come home from university during vacations you can expect bills to leap up. The point is that moderating the amount we shower and the time spent doing it are more important than simply not bathing.

One thing most of us can do is to be more careful about the amount of water we heat in kettles. Each time you do this a little energy is wasted. But this is repeated a number of times in a day. Modelled for a family of four, the extra cost of electricity used came to £70 in a year.

Cooking is another area where opportunities exist to make savings. There are two ways in which energy is wasted, heating up more water than necessary and evaporating water to no useful purpose.

When cooking over rings, there is no benefit in allowing water to be heated above a gentle simmer. The temperature of the water is what effects cooking speed and boiling water is at 100^oC, no matter how high the ring is set. Over heating only leads to evaporation. Similarly, boiling without a lid on pans will lead to needless loss of water as vapour. It is also worthwhile to ensure that the saucepan size matches the size of the ring. Many gas cookers have burners that suit different sizes of pan.

For more ideas about saving energy in cooking see also electrical appliances.

Using washing machines are another day to day job where savings can be made. Modern A rated machines are at least 40% more efficient than older machines, many are 50% better. Even bigger savings than this can be made by washing at the lowest temperature available. Modern powers perform well down to 30^oC (though if you are visiting hospital 60^oC should be used to eliminate any hospital ?super bugs?).

Although it is more efficient to produce hot water from the central heating rather than heat it up in the machine, modern machines use very little water so by the time it has finished filling, the hot water will only just be coming in through the pipes. The result is that most of the hot water drawn will be cooling down in the pipes. For this reason it is best to only connect the machine to the cold water.