Designers and owners are continually bombarded by claims of equipment efficiencies. Industry groups such as ARI, AMCA or CTI have been set up to validate these equipment efficiencies to give these claims credence.
However, it isn't the equipment efficiency that drives the energy use of the building, but the overall efficiency of the system that the equipment is part of.
Steve Kavanaugh, University of Alabama Professor, ASHRAE fellow and author of the ASHRAE design guide for ground-loop heat pump systems (with Rafferty) stresses the importance of the system efficiency. He has also provided (free of charge) a handy tool to calculate the system efficiency of typical HVAC systems, given the efficiencies of their component equipment.
This tool (HVACSysEff06)is available at Steve's Geokiss website software download page.
Take a look around--there are some other interesting tools there, too.