Any suggestions for insulating the shutter for a whole house fan?

Here is some information for adding insulation to a whole house fan shutter.

Consider using  a foil-backed or kraft-backed rigid foam insulation board . It is easy to cut. Cutting pieces into strips and affixing them to each individual shutter being careful not to make them too wide or long to interfere with the shutter motion you could help prevent heat migration through the shutter. However, be mindful that adding insulation to the shutter louvers will increase the weight of each one and could pose problems with the fan having to lift more weight when it is started. Also, if the insulation is thick it will reduce the area available for air to pass through the shutter and may generate some additional airflow noise during operation.