If you are building a true 8 star house then spending $30k on HVAC that will still costs to run seems a bit wastefull aqs the house "should" retain heat well.
The COP is all that matters and the geothermal HVAC ranges from 3 to maybe 4.5 which modern reverse cycle AC will also achieve and beat. Heck buy 5 quality split systems so you only need to heat of cool certain areas of the house and suddenly you are using much less power than a geo unit that does the whole house. Even better spend $10k on a ducted central reverse AC and then put $20k of panels. You will never have an elec bill and the house will be heated for free.
I'm not sure what you mean when you say 3 . Not much point having a heating system ( or cooling ) if there are times in the year when it simply doesn't work. I just checked the Daiken site and theirs heat even when -20 outside and has a COP of 5.9
So are you planning on being off grid and Geo HVAC or one or the other? In terms of solar hot water with a good system you will use bugger all elec, lpg or wood for most of the year.
