Hi I am thinking of installing a whole house fan in my home. My home is about 2700 Square Feet exclusive of a buried basement (which would be about 1285 sqft whole out of which 785 is finished). I am wondering if I need to go in for the traditional whole house fans (like the Dayton or Airvent) probably a 30" one. However, I am a little skeptical abt cutting the joists (mine are 24" centered) to install these. I came across these tamarack and airscape fans which do not need the joists to be cut open. Are these fans quite effective? The other draw back with the traditional fans is the insulation in winter months (I live in DC area) and the available net free venting area in the Attic (as per rough calculations, I would need a 8Sqft venting area for the 30 in fans). Which one would you recommend? Thanks Ram