: Compiler support for power and energy management is effective in reducing power and energy consumption of programs. Compilers typically take single programs as input without the knowledge of other programs that may run at the same time on the target machine. This work investigates the benefits of optimising sets of programs with the goal of reducing overall disk energy. We obtained physical measurements on two laptop disks. The experiments show that inter-program optimisations have significant energy savings over individually optimised programs. Energy savings ranged up to 49% over the individually optimised program versions and up to 82% over the unoptimised versions. Across both disks, the average energy individually optimised and unoptimised versions were 25% and 65%, respectively.