We are happy with our Zehnder HRV. My parents have a pretty basic Fantech unit in their wing, that works fine.

In addition to this board GW has an HVAC forum and there also are a bunch of good articles on Green Building Advisor. Good luck!

No such thing as too tight. The tighter the better. Someone just posted this HVAC question about HRVs with some good replies but an ERV or Supply/Exhaust-Only system might be more appropriate for your climate. I think all new homes should include a means of outdoor air ventilation, whether they build "tight" or not.

Spray foam doesn't equate to tight houses but usually helps. The only way to measure tightness is with a blower door test. Strongly suggest you get Energy Star certified to ensure your home is third party tested and meets other minimum performance criteria related to health, safety and comfort.

How many inches of foam (assuming open cell) is the builder planning for the roof deck? Our building industry is rampant with below code levels of spray foam at the roof deck. You should be installing R38 in your climate as a minimum but R49 might be cost-effective with long term ownership.

Thanks SB, after reading a very good article on Green Building Advisor, we are now going to go with closed cell on the deck and then open cell everywhere else. In speaking to our HVAC folks, we are going to introduce another method of fresh air exchange separate from the HVAC that can be adjusted. Blower door test will be done, it is code here and a requirement. We just have a very productive general meeting yesterday and did not get to R levels but I agree, I'd like to try to end up with R49 but for sure NO less than R38. Our HVAC contractor is very good. We met with several builders and told them, under no uncertain terms we are selecting our on HVAC company. If that was problematic, well they would not build our house. Our builder is very good about that and also on offering thoughts to save money and on board with all of our thoughts on saving where we can.

Building America profiles real world approaches to tight homes in hot humid climates.

"Your house has to breathe" is a phrase much beloved by tradespeople who don't care for detailing. It's an all-purpose excuse that sounds so plausible because of our natural tendency towards anthropomorphising everything we see. Just my view. (My cat agrees.)