Slightly more expensive($300 for a system) you can install a Heat Recovery Ventilator (HRV). A HRV will bring in fresh air into your home and exhaust air from your home while recovering 80% of heat/cold energy in your air. When the system is tuned correctly you pressurize your home, eliminating air infiltration from gaps and cracks in your home exterior.
And there is also the RH % in your home. 75 degrees with 90% humidity is not very comfortable, however that same 75 degrees with 30% humidity isn't that bad.