There are several places within Surple where you can see your highest consuming sites.
You can normalise both of these leaderboards by variables such as area and number of rooms if the relevant metadata has been entered for all of your sites. You can add metadata for your sites from the Sites page by clicking the edit icon next to a site in the map or leaderboard.
Another way to identify your highest consuming sites is by looking at the colour of the markers on the Sites map. The highest consuming site will have a red marker, the lowest will have a green marker, and the other sites' colours are determined by how much their consumption differs from the lowest consuming site.