(1) This Section applies to,
(a) windows, doors and skylights separating conditioned space from unconditioned space or the exterior, and
(b) main entrance doors.
(2) For the purpose of this Section, the term “skylight” refers to unit skylights, roof windows and tubular daylighting devices.
(3) For the purpose of this Section, the term “doors” includes glazing in doors and sidelights for doors.