Thirty years ago, most attics were vented and unconditioned, so they were cold in winter and hot in summer. These temperature swings didn’t matter much, though, because the attics had insulation installed on the attic floor. The attics were outside of the home’s thermal envelope.
These days, builders can choose between a traditional unconditioned attic and a conditioned attic. Conditioned attics are sealed rather than vented. Since the insulation in a conditioned attic follows the roof slope, the temperature in a conditioned attic is close to the temperature in the rest of the house.
My last article on conditioned attics was written a decade ago. It’s time for an update.
The problem is attic ductwork
The main reason that anyone talks about conditioned attics is that some builders want to install ducts in the attic. Installing ducts in an attic is a bad idea, but many builders don’t know that. While locating ducts in an attic reduces installation costs for the builder, it increases energy costs for the homeowner.
Here are the main points to remember about attic ducts and attic mechanical equipment: