Energy Recovery Ventilators
Why energy recovery ventilators?
Here in Texas we have lots of humidity. Couple that with a tightly built home and you may find a need to reduce the amount of humidity in the home and expel the stale air. Most homes built within the last 15 to 25 years are considered tight construction. Vapor were barriers installed on the interior side of exterior walls and in ceilings between the attic and conditioned space, typically plastic. Contractors have gotten away from this at least most especially here in the South where there is lots of humidity. I know of one contractor that cuts slits in the paper backing of insulation batts to allow the moisture to escape and some recommend insulation on exterior walls without the paper backing.
Humidity is one problem. The other is indoor air quality. Recent studies show that average size homes should have .35 air changes per hour. That means replacing the stale, C02 saturated indoor air with fresh outside air. I know people that never open the windows on their home-ever. The only air exchange they have is when the door is briefly opened upon entering or exiting the home. They also complain about constant sneezing and coughing. Wonder why?
ERV Required Areas
HRV Required 
HRV Recommended 
HRV Recommended 
HRV or ERV* w/Defrost Recommended 
ERV* Required
