What is a SAP rating? SAP = Standard Assessment Procedure measured on a scale 1 to 100. It is the calculated annual energy cost for space, water heating and lighting of the dwelling per square meter of the dwelling. The cheaper the cost per square meter the better the SAP rating. Score of 1 = Low energy efficiency = very expensive Score of 100 = Highly energy efficient = no cost In reality to score close to 100 the property would have to sell energy back to the grid.