I recently had an FMI fireplace installed in my house and now that winter is here there is cold air coming in from top and bottom louvre area. There was insulation in the dog-house when installed but I am not sure if that is good enough. What other actions can be taken to stop the cold air drafts when fire place is not in use?

You should have it checked by the installer to insure the venting is working as designed.

you can install you can install you can install a flue shut off. there may also be a flap on the exterior vent that is stuck open.

Be aware however if these are not opened prior to use you can get carbon monoixide poisoning.