Looking at the picture on the left, we have three main problems with this attic (two you can see, one you can't). One, there's not enough insulation. The yellow BATT insulation (featured on the left) is barely to the top of the floor joists (meaning there should be at least 6" more). Two, there is no air sealing (this you can't see). We need to get underneath the insulation to fix this. Third, the whole house fan is completely out in the open (acting as a major source for unwanted air leakage).
To fix the air leakage, CHS pushed aside the old insulation and caulked any penetrations that were facilitating this issue. To bring insulation up to the BPI recommended standard, we blew in closed cell cellulose insulation. To stop the outdated whole house fan from leaking air, we constructed a 2x4 frame with a hinged top (insulated with 2" of foam board) and installed a string and pulley to allow for easy opening.