The following is from the 2020 FBC, Energy Conservation:
C501.7 Building systems and components.
Thermal efficiency standards are set for the following building systems and components where new products are installed or replaced in existing buildings, and for which a permit must be obtained. New products shall meet the minimum efficiencies allowed by this code for the following systems and components:
Heating, ventilating or air-conditioning systems;
Service water or pool heating systems;
Lighting systems; and
Replacement fenestration.
If the roof replacement is part of a building alteration, then the following applies:
C503.3 Building envelope.
New building envelope assemblies that are part of the alteration shall comply with Sections C402.1 through C402.5.
C503.3.1 Roof replacement.
Roof replacements shall comply with Table C402.1.3 or C402.1.4 where the existing roof assembly is part of the building thermal envelope and contains insulation entirely above the roof deck.