My wife and I are building a house in Houston which is about 4000 sq feet. The builder's base unit is a 13 SEER Carrier unit with allergen filtration systems, fresh air damper, ultraviolent light system, and programable t-stat. It has 3 zones (Master suite, remainder of downstairs, and upstairs)

The builder is offering an upgrade to the Carrier Infinity system (for some $'s of course) which per the subcontractor would be a 14.5 SEER 5 Ton unit downstairs and a 16 SEER 2.5 Ton unit upstairs. It would also include all the filtration, fresh air and zoning as the standard system plus the Infinity controls.

We plan on staying in the house for the long haul and are leaning toward selecting this system. I'm trying to get a decent feel for what % savings on our electricity we could expect each month? 5%, 10% 25%??

Any insight would be appreciated.