My daughter has very bad allergies and a very weak immune system

We are building a new house and we are entirely focused on creating as clean an environment as possible for her (no carpets, no rugs, etc).

Clearly a whole house HEPA filter seems to be the way to go - what we would like your opinon on is are other add-ons like charcol filters, UV lamps (Non ozone), gas phase filters, etc that will improve upon a whole house HEPA.

If i could create a clean room at home i would, but that costs hundreds of thousands - we are comfortable spending up to $30k - $50k on the HVAC equipment for a our 4,000 sq foot house (not including duct work etc) to make it the best environment for her as possible

Thank you in advance - all advice is much appreciated