We've got a 5 storey wood frame building pursuing LEED Silver. Our current dilemma is we have large and long units. Approximately 80% of the suite can be natuarlly ventilated to ASHRAE 62.1-2004. Our problem is the 25' rule within the same space, which in our cases are dens and kitchens. The dens have no door and have a permanent opening as required by ashrae but the farthest wall is not within 25'. I'm sure some people have run into this problem, I see some people have put transfer fans in their units, how exactly was this designed?
Currently our design incorporates a geothermal water to air heat pump c/w with a 4" round outside air duct ducted to the return air duct of the heat pump. We also have a continuously running HRV exhausting from each suite and supplying fresh air to the corridiors. I realize this is a hard thing to input on the energy models (so i've been told) and we may incur an energy penalty for reheating outside air for each unit, the project energy modeler is in the midst of modeling this to ensure we still get our requried energy points.
Has anyone been successful with the proposed system above or have an example of something that has been successful?