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.

(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.