At this time Snugg Pro does not model the efficiency of whole house fans, although the installation of a new system may be added as a custom recommendation. Follow the reference link below to find estimated equipment cost and estimated cost of operation.

A whole house fan can be used as the sole means of cooling or to reduce the need for air conditioning. If both methods of cooling are present, seasonal use of the whole house fan may yield the optimum combination of comfort and cost.

During the winter months (and in summer when air conditioning is used), a whole house fan represents a potential energy loss because it is essentially a large, uninsulated hole in the ceiling. Since standard fan louvers do not insulate or seal tightly, a cover should be constructed to airseal and insulate this opening.

Determining the amount of airflow in cubic feet per minute (cfm) that the whole house fan should provide involves a simple calculation.

Multiply the total gross square footage of the house (include upstairs area) by the ceiling height (typically 8 feet). Select a fan that delivers between one-half to one time that amount of cfm at 0.1" static pressure. For example, a 25' x 40' one-story home is 1,000 square feet and would need an 8 x 1,000 x 1 / 2 = 4,000 cfm fan or better. A two-speed unit that delivers 4,500 cfm at the high setting (240 watts) and 3,200 cfm at low (120 watts) should be adequate.

Reference:

Whole House Fan: How to install and use a whole house fan (Written and prepared for the U.S. Department of Energy by: Southface Energy Institute & Oak Ridge National Laboratory)