J5.5 Ductwork insulation
(a) Ductwork and fittings in an air-conditioning system must be provided with insulation—
[No duct insulation required for non conditioned air in ducts]
(i) complying with AS/NZS 4859.1; and
(ii) having an insulation R-Value greater than or equal to—
(A) for flexible ductwork, 1.0; or
(B) for cushion boxes, that of the connecting ductwork; or
(C) that specified in Table J5.5.
[The R-value noted in Table J5.5 is the minimum material R-value]
(b) Insulation must—
(i) be protected against the effects of weather and sunlight; and
[Weather and sunlight deteriorate the insulating properties of the insulation.]
(ii) be installed so that it—
(A) abuts adjoining insulation to form a continuous barrier; and
(B) maintains its position and thickness, other than at flanges and supports; and
[To prevent condensation on cold surfaces.]
(iii) when conveying cooled air—
(A) be protected by a vapour barrier on the outside of the insulation; and
(B) where the vapour barrier is a membrane, be installed so that adjoining sheets of the membrane—
(aa) overlap by at least 50 mm; and
(bb) are bonded or taped together.
(c) The requirements of (a) do not apply to—
(i) ductwork and fittings located within the only or last room served by the system; or
(ii) fittings that form part of the interface with the conditioned space; or
(iii) return air ductwork in, or passing through, a conditioned space; or
(iv) ductwork for outdoor air and exhaust air associated with an air-conditioning system; or
(v) the floor of an in-situ air-handling unit; or
(vi) packaged air conditioners, split systems, and variable refrigerant flow air-conditioning equipment complying with MEPS; or
(vii) flexible fan connections.
(d) For the purposes of (a), (b) and (c), fittings—
(i) include non-active components of a ductwork system such as cushion boxes; and
(ii) exclude active components such as air-handling unit components.
Example: Insulation required