Installation of upgrade kits are energy efficient and save you money in maintenance cost and utility usage.
Some models can be upgraded from belt driven evaporator fan motors to EC fans. That means no more belts, in turn saving on maintenance costs and utility cost. Other models you can upgrade with a VSD and inverted duty motor which still is being belt driven, but you can save some money on utility.
Having a deteriorated condensing coil can cause your unit to work harder and drive your utility cost up. Replacing your existing Liebert fin and tube condensing unit with the MC series (microchannel) condensing unit and doing a few other upgrades can save you money in the long run.