I buying a house in Las Vegas and the builder is only offering an SEER 13 Goodman unit with an 80% Efficiency gas heater.

I had contacted the contractor to find out what options I had since the builder would not change anything (citing the cost by the contractor to engineer the system for these upgrades). The contractor ignored my, without any call back or email and talked to the builder who told him to IGNORE me.

Well they installed their base unit in the attic space. The roof has gone on and once the wallboard goes up, I know you will have to rip a lot to make any physical changes to the unit.

I had wanted to go with a Lennox dual-stage compressor, high efficient A/C with the 98% fully variable heater since I had this combination before and the quiet, subtle performance was awesome.

I realize that is probably not going to happen now without a LOT of extra cost.

Is there anything I can do upon closing to swap out the evaporator/condenser units to higher efficiency. What about the variable speed high efficiency DC motor replacement? Can I at least upgrade to the SEER 16 or 18 unit with the same air handler?

I really cannot believe that in a part of the country with the highest AC demand they are not required to ALLOW me to pay at MY COST for upgraded units. There will be a big difference between SEER 13 and SEER 21. That is about a 40% less KWH usage for the same cooling.

Your opinions are welcome. I understand the cost savings aren't going to be huge enough to ever pay for the Lennox premium especially since a unit is already in there, but it is about consumption and doing my part to be more efficient.