My focus here is on the adjustment of ceiling insulation R values (R4.0, R5.0, etc...), due to loss of ceiling insulation mainly from recessed downlights as the area of ceiling insulation will be reduced. The loss of insulation will be required to be compensated for by increasing the R-Value of insulation in the remainder of the ceiling. This criteria has been added in BCA Section 18.104.22.168(e). Refer to Table 22.214.171.124b taken from BCA.
For a dwelling with no downlights, the ceiling insulation adjustment will not be required. Ceiling insulation to remain as is.
For a dwelling with 20-off downlights.
Ceiling area penetrated is: 3.8
Assuming total ceiling area: 200
Percentage penetrated: 2.43%
Ceiling insulation R3.5 required for 6-star. Adjustment is: R4.8
This adjustment is to apply for single-storey dwellings. For double-storey dwellings, adjustment will apply to ceilings exposed to the elements.
FAQ: Does this ceiling insulation adjustment or quantity of downlights affect star rating?
Answer: NO. Ceiling adjustment does not affect the star rating energy efficiency.