Energy efficiency means "using less energy to provide the same service". This can be applied to the energy you use in home from day to day.
When you replace a single pane window in your house with a new energy-efficient one, the new window prevents heat from escaping in the winter. So you save energy by using your furnace or electric heater less while still staying comfortable.
In the summer, efficient windows keep the heat out, so the air conditioner does not run as often and you save electricity.
Energy efficiency is not the same thing as energy conservation.
Energy conservation is reducing or going without a service to save energy.
For example: Turning off the air conditioner all together is energy conservation. Using the air conditioner wisely by changing out the filter, getting regular maintenance, and investing in an energy star air conditioner are all ways to be energy efficient.
Both efficiency and conservation can reduce greenhouse gas emissions.
Anywhere energy is used, there are opportunities to increase efficiency. In most cases, energy efficiency measures will pay for themselves over time in the form of lower energy bills.How quickly they pay back their investment depends on a lot of factors, such as the cost of energy, and the overall use of the measure—for example, how many hours an appliance is on. Weather is a factor when the measure is related to maintaining environmental conditions—in air conditioning, heating for example. In the very hot summer months, you will use more air conditioning than in the Spring and Fall months.
