Hi all,
I am in the process of building and am expecting to have the energy efficiency report/star rating come through soon. Apparently it already reaches the 6 star rating without taking into account any insulation, so hopefully I can get up to around the 7/7.5 mark as I have both reflective blanket foil insulation as well as batts.
What baffles me though is the whole energy rating system. I know it takes into account orientation, window size and location, climate, roof/wall colours, insulation, building material, etc, but I find it hard how the assessors come up with some of the star ratings.
For example (real examples)
House 1 - Dark roof, Medium external walls, no wall insulation, block construction (core fill), blanket foil insulation under roof, living areas facing South, most bedrooms facing west, Zone 1 Climate - 7 stars. Outdoor area (no fan) extra .5 star - 7.5 stars total.
House 2 - Medium roof, medium external walls, sisalation to walls, block construction (solid fill), blanket foil insulation under roof, living areas facing SE (direction of cool, summer trade winds), bedrooms facing North, laundry, garage and one bedroom facing west, Zone 1 Climate - 5 stars. Extra 1 star for outdoor living area with ceiling fan - total of 6 stars.
I know the system takes many more things into account, but it still doesn't make sense to me how House 1 can be substantially better than House 2 when they are both around the 230sqm mark - almost seems like the assessor threw some random numbers into the software. Can anyone with experience in energy efficiency shed some light on how the whole thing works? Obviously some things must have bigger influences than others (i.e. I have hard window size and location has the most impact).
Cheers,
Dale