So, unless you’ve recently updated your building’s attic insulation, you probably don’t have as much protection as you thought you did.
Another reason for energy loss through the attic is emission, or radiant heat transfer, which is essentially the transfer of heat through empty space, rather than by direct contact. If you’ve ever felt the warmth of the sun on your face, then you’ve experienced heat transfer by emission.
Adding attic insulation such as fiberglass or cellulose doesn’t fully address this type of transfer because they protect mostly against convection and conduction, two other types of heat transfer.