Every industry has its problems and the HVAC business is no different. Let’s look at how our industry got into the mess of great equipment installed on not-so-great duct systems and one way you can prevent it.
An HVAC contractor called in to solve a comfort problem will usually first address the equipment. Some stop there, but more progressive contractors then look at the ductwork. Finally, comes the insulation.
The "magic number" 1.08 is convenience factor. It is a bunch of math combined into one factor as a shortcut, although sometimes more precise calculation is better.