Transfer air into residential units

Hi, Mike- It generally works out best to document natural ventilation for residential rooms where possible rather than mechanical ventilation. For rooms other than kitchens and bathrooms, you should normally have at least 4% openable area at the windows which is all you need for natural ventilation. The bathrooms and kitchens don't have required outdoor air rates, only required exhaust rates. If using mechanical ventilation instead of natural ventilation in the living areas and bedrooms, you'll need an exhaust fan to pull the air from the corridor into the rooms in the residence units. When you need or want to calculate mechanical ventilation, you'll need to use the zone air distribution effectiveness (Ez) numbers for exhaust driven air distribution. When makeup air is drawn in on the opposite side of the room from the exhaust or return inlet Ez is 0.8. When makeup supply air is drawn in near to the exhaust or return inlet Ez is 0.5. The International Mechanical Code lets you just put the required outdoor air into the adjacent space that you are pulling makeup air from. With an Ez of 0.5, you would have to put double the outdoor air into the adjacent space. However, for LEED compliance with ASHRAE 62.1, I think you'd have to use the equations in Appendix A of Standard 62.1 under the paragraph "Secondary Recirculation Systems". You can see the 62.1-2010 version of this on ASHRAE's website for free under the Standards & Guidelines tab, if you don't have access to 62.1-2007.