hi to all!

What a great site!  My wife & I are building a house next year, & I have been posting in the geothermal & SIP forums.  We're getting closer to figuring out our plan.   We are definitely doing geothermal heat, leaning toward SIP construction.  The house will be approx 2000 sq ft walkout ranch with another 1000+ finished in the basement, so I'm trying to figure out the best way to heat the basement.  I'm pretty sure we're going to do forced air heat throughout the house.  As much as I like the idea of radiant heat, I don't think our budget can support it. My understanding is that we would need all of the ductwork anyway for the A/C in the summer.  Because we are building a very tight house, we will need an HRV also, which I think also relies on ductwork.  For those reasons, my understanding is that we would have to install basically the same system that would would normally install for forced air, PLUS the radiant system.

When it comes to the basement, though, I'm wondering if it would make sense to do radiant heat vs. additional ductwork for forced air heat.  Can anyone ballpark the cost differential between the two, if we did radiant only in the basement?

To save money you could just install the radiant tubes in the basement floor yourself. Then later you could add all the above cement parts. It is pretty inexpensive if you do it yourself. Menards has PEX with oxygen barrier on sale this week, although it goes on sale about every 6 months. Either way make sure you put at least 2 inches of insulation (pink board or similar) under the cement.

Personally I would duct the basement for forced air for AC reasons either way. I doubt you would save that much cutting just the basement out of the HVAC. And if you are going to use radiant on the main floor you have to get it all stapled up before everything else goes in and you would also need the metal heat fins which about doubled the cost of the pex, but worth it. For us doing the main floor was more expensive and time consuming than the poured basement slab, but we ran all the pex ourselves and let them install a forced air system with the basement zoned separately.