Energy performance certificate is a ranking system that summarizes a building's energy efficiency. The building is graded from A to G, and the EPC will offer suggestions on how to raise your home's energy rating at the lowest possible cost. Many countries utilize energy performance certificates. Energy Performance Certificates (EPCs), similar to the multi-colored sticker on new appliances, inform you how energy efficient a building is and assign it a rating ranging from A (extremely efficient) to G. (inefficient). EPC is required when constructing a new building or marketing an existing structure for sale or rent.