An Energy Performance Certificate (EPC) will tell you how energy efficient a property is, showing the estimated energy usage over three years. From this it gives it a rating between A to G (an 'A' rating being very efficient). An EPC certificate will remain valid for 10 years from the date the report is produced.
EPC certificates could help you to buy a home that wastes less energy, show you what your energy bills might be and give you an estimate of the carbon emissions it produces.
If you're not moving home, an EPC certificate could also help you with a range of energy-efficient ideas for your home. Even if you rent, you could still try some of the smaller ideas, such as draught-proofing.