Energy efficiency means using less energy to provide the same service. For example, a fluorescent bulb is more efficient than a traditional bulb as it uses much less electrical energy to produce the same amount of light.
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The phrase 'energy efficiency' is often used to describe any kind of energy-saving measure. However, it should be distinguished from energy conservation.
Examples include turning down a thermostat in the winter or walking to the shops rather than driving there.
Increasing energy efficiency often means spending money up-front.
This makes efficiency improvements an attractive starting point for reducing carbon emissions.
The extent of the savings and the techniques that are required depend on the situation and location. For homes in cool countries, the most effective measures include increasing insulation and switching to more efficient appliances and light bulbs.
Many of them have achieved savings of around 25% after undergoing a refit to increase efficiency.
Energy-intensive industries, such as iron, steel and cement manufacture need huge amounts of energy. But even they have become more efficient over time due to new equipment and better re-use of waste heat.
Also, the installation of efficient, correctly sized motors can result in energy savings of 20-25%.
Vehicles have also become more energy efficient over the decades thanks to factors such as improved engines and lighter, more aerodynamic designs. Of course, much more can be done.
When comparing electric and non-electric appliances, it is also important to consider the efficiency of the power source.
But only if the electricity comes from fossil fuel power plants, which are highly inefficient because they lose much of the energy as waste heat.
Improving energy efficiency does not necessarily mean reduced CO2 emissions. If the energy is supplied from fossil fuels, such as petrol in a car or electricity from a coal-fired plant, then improved efficiency will cut emissions. But if the energy is supplied by a low-carbon source, like nuclear, wind or solar power, then improving efficiency may have little impact on emissions of CO2 because such energy sources produce power with considerably lower amounts of CO2 emissions.
Energy efficiency is always a good idea.
For example, by insulating your home either your present standard of comfort can become more economical because of lower energy bills or you can increase your standard of comfort (by enjoying a higher room temperature) at the same cost, but without saving energy.
Nonetheless, improving energy efficiency is a key tool for reducing CO2 emissions, alongside energy conservation and low-carbon energy sources.
A Non-domestic buildings, on the other hand, need a focus on ventilation and air-conditioning, in addition to lighting, heating and appliances.
B In many cases this initial investment will be paid back in the form of reduced energy costs within a short time period.
C The savings may vary considerably.
D Switching from a 90% efficient gas boiler to a 100% efficient electric heater may increase energy use and emissions.
E The potential exists for further improvements.
F Whether it results in energy savings depends on what you do with the money you saved.
G For instance, a hot pipe containing a chemical that needs to be cooled can be used to warm up other chemicals.
H That's a broader term which not only includes changing the efficiency to reduce the amount of energy you use, but also dropping a service in order not to use energy at all.
I Similarly, an efficient boiler takes less fuel to heat a home than a less efficient model.
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