What is 'efficiency' and how can I improve it?
Energy efficiency in the context of consumption is the measure of how much energy is put to use as a ratio to how much is wasted.
Take an incandescent light bulb for example, incandescent light bulbs are notoriously inefficient by modern standards, this is because much of the energy used to provide light is wasted through heating effects. Have you ever noticed how hot some light bulbs get? If it feels hot then it's very likely you have an incandescent light bulb!
The basic formula for efficiency is:
Efficiency (%) = (energy out)/(energy in) x 100
The energy out would be the useful component, I.e., the light which projects from the bulb. Whereas, the energy in would be the energy demanded by the bulb in the first instance – this is the energy investment.
For the incandescent bulb:
Efficiency (%) = (3.8 W)/(40 W )=9.5%
So, for the energy invested, only 9.5% is providing light – this is the useful or desired component.
As technology has advanced, there are more sophisticated methods to improve the energy investment. For the case of the incandescent bulb, LED bulbs are potentially 10x more efficient.
The same calculation can be seen for an LED bulb: