I'd suggest you consider the environment around your house - permaculture materials will help here as sustainable habitations are a strong focus. You've sugges

I'd suggest you consider the environment around your house - permaculture materials will help here as sustainable habitations are a strong focus. You've suggested a 'massive concrete house' without stating size (massive is very subjective) or why you want concrete (a very expensive material, in $-cost, environmental costs, and maintenance / repair). You haven't indicated what climate you're in, or the landscape you're working with. Passive solar heating works well with concrete floors on an equator-facing house (assuming you're outside the tropics) with thoughtfully designed awnings, but a 'whole concrete house' will likely backfire if you're intending to reduce on-going HVAC costs.