Some random thoughts from my house build....
Look at getting a radiant barrier on your roof decking, which should help keep attic temps down. Agree with folks on air sealing -- recommend reading up on greenbuildingadvisor or energyvanguard blogs.
I've read many horror stories on spray foam....it works fine most of the time, but when it goes wrong it goes really wrong and is a pain to remove. I tried to avoid it where I could, and just using it for crawlspace walls and rim joists. In my experience, builders think spray foam has some kind of "magic", but really the trick is just air sealing, which you can get by taping your sheathing seams (using zip or just OSB/plywood) or using some kind of vapor-permeable membrane.
re: rigid vs flex duct -- My insulation contractor did a great job with the batt insulation in my vaulted bedroom ceiling, but I'm pretty sure they crushed the flex duct for one of the supply vents in there. The upside to flex though is fewer seams/connection points.
On HVAC, the upside of the variable speed systems is they can modulate to lower output, so run longer/more to do a better job of dehumidification. Contractors often oversize systems, and if it's single speed then you'll have the system run full-out for very short cycles, doing a poor job of getting even temp throughout the house and removing humidity from the air. Variable speed systems are better in that regard, especially if you can't trust your contractor to not oversize your system (the contractor our builder commonly uses wanted to oversize our system by more than double).
Did the contractor do a Manual J to determine the load, and from there a manual S to size the system? I'd recommend asking to see it - their response will tell you a lot, and you can verify their inputs are correct (design temps, # of occupants, load from appliances, insulation values, etc). Again, we had a bad experience with our builder's contractor but luckily had hired a consultant to do the calcs for us so we were informed consumers.
Look at getting a radiant barrier on your roof decking, which should help keep attic temps down. Agree with folks on air sealing -- recommend reading up on greenbuildingadvisor or energyvanguard blogs.
I've read many horror stories on spray foam....it works fine most of the time, but when it goes wrong it goes really wrong and is a pain to remove. I tried to avoid it where I could, and just using it for crawlspace walls and rim joists. In my experience, builders think spray foam has some kind of "magic", but really the trick is just air sealing, which you can get by taping your sheathing seams (using zip or just OSB/plywood) or using some kind of vapor-permeable membrane.
re: rigid vs flex duct -- My insulation contractor did a great job with the batt insulation in my vaulted bedroom ceiling, but I'm pretty sure they crushed the flex duct for one of the supply vents in there. The upside to flex though is fewer seams/connection points.
On HVAC, the upside of the variable speed systems is they can modulate to lower output, so run longer/more to do a better job of dehumidification. Contractors often oversize systems, and if it's single speed then you'll have the system run full-out for very short cycles, doing a poor job of getting even temp throughout the house and removing humidity from the air. Variable speed systems are better in that regard, especially if you can't trust your contractor to not oversize your system (the contractor our builder commonly uses wanted to oversize our system by more than double).
Did the contractor do a Manual J to determine the load, and from there a manual S to size the system? I'd recommend asking to see it - their response will tell you a lot, and you can verify their inputs are correct (design temps, # of occupants, load from appliances, insulation values, etc). Again, we had a bad experience with our builder's contractor but luckily had hired a consultant to do the calcs for us so we were informed consumers.
