I'm not familiar with heat exchangers.
I was thinking if I could build my dream house I would have solar tiles (roof tiles that act as solar panels), a whole room dedicated to generators/batteries, maybe additional roof space for more solar, some wind turbines, some sort of graywater system to filter used water from sinks, mechanical effluent system (solar powered), triple pane windows with argon and low e tinting (maybe even see if its possible to get some that act as solar panels), and insulated doors. I would want a large garage that is well insulated.