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Energy efficiency

Greenhouse gas emissions emerging from industrial chimneys (Jan Smolik)

There are several inter linked factors contributing to our ever increasing use of energy. One is our growing population which is unlikely to stabilise before 2050 and at a total of 9 billion people. Contrast this with the world’s population 100 years ago which was around 2.0 billion. Another factor is our own individual use of energy which has increased dramatically in developed countries since the start of the industrial revolution in the home and at work.

Our major uses of energy include transport, generation of electricity and providing space and water heating in buildings. If we define energy as the capacity for doing work then we have developed machines over a period of many years to do the work that was previously done by hand. The energy that these machines consume has been provided primarily by coal, oil and gas and it is in the combustion of these fossil fuels that greenhouse gases like carbon dioxide are produced as a by-product.

Greenhouse gas emissions emerging from industrial chimneys (Jan Smolik)

? Why has our energy usage increased over the past 100 years? What usage do you think is making the greatest contribution to global warming? 

There are 3 basic ways in which we can reduce the environmental impact of our energy use –

  • Using less energy
  • Using energy more efficiently
  • Converting our energy sources from fossil fuels to renewable sources; we have considered these sources and noted how they can be used around our home in the renewable source section

Average energy consumption

As described in the carbon footprint section, in the UK, space heating consumes the largest amount of energy, but car usage produces the largest emissions of carbon dioxide. In countries further north more energy might be consumed because of the more extreme climate while in countries to the south, less energy will be required. The level of thermal insulation is an important factor in determining how much energy will actually be consumed.

What is also significant is how much less energy is consumed by public rather than personal transport.

Using less energy

 Energy use, European style (Jan Smolik)

In order to reduce our own energy consumption, each of us has to consider how and where we use energy. This is illustrated in the adjoining sketch of a living room with its energy consuming appliances such as lighting, TV, radio and heating.
Energy use, European style (Jan Smolik)

Possible actions to reduce such energy use include –

  • switching off lights when leaving a room
  • switching off appliances not being used at the mains rather than the remote
  • reading a book rather than watching the television

If you had a garden, you should also consider growing your own fruit and vegetables thereby decreasing the ‘food miles’ associated with transporting and distributing such items.

? Survey your energy use over one day and identify where you could save energy?

Using energy more efficiently

We use many energy consuming products in our daily work, leisure time and at home. Apart from making less use of these products, we can often use them in a more efficient way. Many of these ways are logical and simple to execute. For example many appliances have an energy saving or sleep mode, which may need activation.

Other ways of efficient energy use include –

  • Washing clothes or dishes for a longer time at lower temperatures.
  • When cooking, a microwave oven can save energy as the heating process is more efficient for certain types of food and recipes
  • Cooking larger portions so that there will be sufficient food for two meals rather than one
  • Taking a shower rather than a bath
  • Placing reflecting panels behind radiators ensures that more heat is reflected into the room
  • Fitting thermostatic valves to radiators so temperatures can be varied in each room depending upon their usage
  • Descaling radiators (refer box)
  • Driving in economy mode as most cars now have computers which calculate fuel consumption
  • Car sharing

? What other ways can you identify of using energy more efficiently ?

Descaler and inhibitors in central heating systems

Radiators in houses are sized to meet their heat loss. If however the water in the central heating system is not maintained at its neutral level (pH 7.0) then a chemical reaction will occur between the water and the steel pipework and radiators resulting in the build up of corrosion products. These products comprise gases which congregate in the top of radiators so limiting the heat transfer area and the build up of inorganic salts on the internal walls of radiators so limiting their ability to transfer heat.

Sachet containing 250cc inhibitor to reduce corrosion in central heating systems


Both these factors can be minimised by adding a suitable inhibitor each year to the central heating system when it is serviced. Typically 250 cc have to be added annually and energy savings can be up to 10% with a similar reduction in carbon emissions

Energy labelling
energy label

Energy labelling is now common in most countries around the world and as its name indicates, describes the energy consumption or energy savings potential of a product and ranks one or more criteria in terms of performance.
The introduction of labelling has had numerous beneficial effects which include –

  • establishing a dialogue between buyer and seller
  • comparing the life time cost of various models which can be defined as the initial cost plus the running cost of energy over its lifetime; other consumables can also be costed such as that of water for washing appliances; the cheapest models may not have the lowest running costs
  • introduction of minimum efficiency standards for energy consuming or energy saving products; this has resulted in the least efficient products being withdrawn from the mark

The illustrated label is for a washing machine and indicates not only the amount of energy and water it uses, but also rates its washing capability.

Energy labelling has encouraged manufacturers to improve the efficiency of their appliances because the incremental cost is often small and consumers are becoming more aware of the cost of energy and its likely impact on the environment The greatest increase in efficiency has been in lighting where incandescent bulbs have been replaced by compact fluorescent and LED bulbs with a corresponding increase in efficiency increase from 10% to over 90%.

Energy efficiency of buildings have also been labelled and these labels are illustrated below and need to be displayed or shown for all buildings when rented or sold.

Energy efficiency and environmental impact labels for buildings



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