Energy efficiency refers to the practice of using less energy to perform the same task. It is achieved by using more efficient technology, changing behaviour, or improving the design of buildings and systems.

Renewable energy sources are sources of energy that can be replenished naturally and do not deplete over time. Examples include solar, wind, hydro, geothermal, and biomass energy.

Energy efficiency and renewable energy sources are linked because using energy more efficiently reduces the amount of energy needed to perform a task, which in turn reduces the demand for energy from non-renewable sources like fossil fuels. Renewable energy sources can then be used to meet the remaining demand for energy, making the overall energy system more sustainable.

One example is using energy-efficient building design and appliances in combination with rooftop solar panels to generate electricity. Another example is using wind turbines to generate electricity for a community and using energy-efficient lighting and appliances to reduce the overall demand for energy.

Using energy efficiency and renewable energy sources together can reduce greenhouse gas emissions, improve air quality, decrease reliance on fossil fuels, and save money on energy bills. It also helps to create a more sustainable energy system for future generations.