Hi!  Yet another question for you all!  I've read varying opinions on this, and possibly it depends on a variety of factors, so I wanted to get your take on our particular home situation.  We are building an ICF home in Central Florida.  Our builder had the HVAC system sized down smaller, since we have an ICF house.  That being the case, do we need to get something like an air exchanger or a dehumidifier for our house? 

I was reading about Sarah Susanka's Green Home here in Florida, and that house was constructed with SIPs.  They said it was so airtight that they got a dehumidifier to work in tandem with the HVAC system, presumably because the Florida air is so humid.  I was wondering whether we do, in fact, need something like this.

Our builder specializes in ICF homes, and he said that, because the HVAC system was sized down so small, it will run frequently and thus an air exchanger or dehumidifier would be unnecessary for our house.  I am doubtful, because I've read about so many others getting additional equipment.  Is this type of equipment truly necessary, or will a small HVAC system keep our house free from moisture & mold?

Any thoughts would be appreciated!
Best regards,
Heather Wright
Our ICF Home Construction Journal http://hmp2z.wordpress.com

Let's just put it this way: All new houses should have some method of introducing fresh air. That said, if the system that your builder is proposing does not allow this, then I would consult someone else.

Especially when you consider how tight an ICF house should be. And having fresh air goes beyond just moisture mitigation, it's a healthier indoor environment.

Good Luck!

hmp2z
Panelcrafter is absolutely correct. There have been two ICF houses built with regular sized HVAC units here in Ft Myers, and they both ended up with Sick House Syndrome. They were cured when the HVAC units were down sized and a positive air exchanger built into the system. A "Manual J" calculation is required on each room to have the unit sized correctly.
A properly sized AC unit will run enough to take the humidity out of the house and keep it comfortable. If you keep the humidity below 50%, mold will not grow in the house.
A positive air exchanger will keep positive air pressure inside the house so that air will move from the inside to the exterior when a door is opened. This helps keep dust and pollen out of the house.
Regards,
Joe

Some ICF houses may need it, but most don't. A properly sized HVAC system is the critical part. Heather I would recommend that you have Richard Rue at energywise structures calculate your HVAC requirements. http://energywisestructures.com/ Thats what I did.