- Subject to the limitations stated in Sentences (6) to (8), the trade-off options described in Sentences (2) to (4) apply only to above-ground building envelope components and assemblies, or portions thereof, of a single building.
- The effective thermal resistance of one or more above-ground opaque building envelope assemblies is permitted to be less than that required in Article 9.36.2.6., provided
- The total areas of all proposed and reference assemblies are equal,
- The effective thermal resistance of one or more other proposed above-ground opaque building envelope assembly areas is increased to more than that required by Article 9.36.2.6., and
- The sum of the areas of all traded above-ground opaque building envelope assemblies divided by their respective thermal resistance is less than or equal to what it would be if all assemblies complied with Article 9.36.2.6.
- The effective thermal resistance of one or more windows, as calculated in accordance with Sentence (5), is permitted to be less than that required in Article 9.36.2.7., provided
- The total areas of all traded windows are equal,
- The traded windows are located in the same orientation,
- The effective thermal resistance of one or more other windows is increased to more than that required by Article 9.36.2.7., and
- The sum of the areas of all traded in windows divided by their respective effective thermal resistance is less than or equal to what it would be if all windows complied with Article 9.36.2.7.
- The effective thermal resistance of one or more portions of floor insulation or ceiling insulation in attics under sloped roofs in buildings that one storey in building height is permitted to be less than that required in Article 9.36.2.6., provided
- The total area of fenestration, excluding skylights, and doors does not exceed 15% of the above-ground gross wall area as calculated in accordance with Article 9.36.2.3.,
- The floor-to-ceiling height measured from the top of the subfloor to the underside of the finished ceiling of the storey does not exceed 2.34 m,
- The distance measured from the top of the subfloor to the underside of the bottom chord of the truss or joist of the roof is not more than 2.39 m, and
- The difference between the sum of the proposed areas of ceilings, or floors divided by their respective proposed effective thermal resistance and the sum of the reference areas of ceilings or floors divided by their respective thermal resistance required Article 9.36.2.6. is not more than the difference between 17% fenestration and door area and the proposed fenestration and door areas divided by the required effective thermal resistance values for windows and doors in Article 9.36.2.7.
- The effective thermal resistance of windows shall be determined using one of the following equations, as applicable:
- RSI = 1/U, where the U-value is known, or
- RSI = 20/(57-ER), where the energy rating is known.
- The reduction in effective thermal resistance of above-ground opaque building envelope assemblies permitted by Sentences (2) and (4) shall result in an RSI value that is not less than
- 55% of that required in Article 9.36.2.6. for above-ground walls and joist-type roofs
- 60% of that required in Article 9.36.2.6. for other opaque assemblies.
- The effective thermal resistances of above-ground opaque assemblies with embedded heating cables, pipes or membranes are not permitted to be traded.
- The effective thermal resistances of doors and access hatches described in Sentences 9.36.2.7.(3) to (7) are not permitted to be traded.