What is the optimal setup for mechanical systems for slab on grade?
...mini-split? As a brief aside - you mention an ERV, which may or may not be the best choice for you; here is our page on choosing between an HRV and ERV
The Edelweiss House (where we installed the mini-split heat pump for heating and cooling) is a very well-insulated and airtight envelope, so it doesn't require a lot of...