Replies

1. 
   jklingel | Aug 09, 2012 02:27am | #1

   It is my understanding that attic fans create a negative pressure in the attic, encouraging conditioned air to leave the house and enter the attic. That will bring in moisture. Not good. (Edit: Martin answered this for another post. See https://www.greenbuildingadvisor.com/community/forum/gba-pro-help/25119/radiant-barrier-warming-house)

2. GBA Editor
   Martin Holladay | Aug 09, 2012 05:16am | #2

   Rocky,
   As John points out, I already answered this question the last time you asked it. ("An attic fan will just add to your electricity bill, and may suck air-conditioned air out of your house, making things worse. More information here: Are Solar-Powered Attic Ventilators Green? and here: Martin’s Useless Products List.)

   Remember: the best way to address this problem is to install insulation on your attic floor.

3. 
   homedesign | Aug 09, 2012 07:20am | #3

   or even better

   MAKE THE ATTIC FLOOR AIRTIGHT....
   and THEN install AMPLE insulation

4. 
   homedesign | Aug 09, 2012 07:41am | #4

   Many Houses are Not-So-Airtight
   In an Air Conditioned House, during the Cooling season...

   the Cold Dense Air inside the House "Spills" out thru Unintentional openings in the lower portions of the house
   AFTER the cold Air spills out... the remaining air can no longer support/resist the Air Above the House
   and then Hot Air SPILLS in thru unintentional openings in the upper portions of the House

   We live at the Bottom of an Ocean of Air

   
5. 
   BobHr | Aug 10, 2012 11:01am | #5

   the op needs to understand the dynamics of heat flow in an attic. for startes the radiant heat of the sun heat the roof deck. Some of the heat is given off by convection both in out of the attic, a little by conduction but most radiating the heat to the attic floor/insulation. Since radiant heat travels through air it finds its way deep into or through the air pockets in the fiberglass insulation.

   The radiant heat is really the cause of your house being hot. You would have to pull an awful lot of air through the attic to give the temp down to outdoor temp but you would still have the radiant heat.

   Like others have said you want to air seal the attic and then pile up as much cellulose as you can. When doing this do what Joe at BSC call continuous soffit venting. That is there needs to be a baffle between every set of rafters not one every 3rd or 4th set of rafters.