Our house plans finally got approved after sitting in the too-hard basket at the council for the last 3 months and we also got advice from the builder today that the energy efficiency came in at only 4.1 which is pretty poor. They advice including cavity insulation to bring it up to 6. The cost of this is just under $3k which I am happy enough with.
Are there any other options we should consider that give decent bang for buck? I looked briefly at double glazing etc. but the cost is prohibitive and I am putting external roller shutters on most of the north facing windows anyway. The house is long and skinny on an east-west facing block so we have long walls and a decent number of windows on both the north and south side (only one window each facing east and west).
We are also considering roof colours. Most of the house is white but we picked a Colorbond Night Sky roof which I am thinking is maybe a bad idea. I looked at the solar absorbance after we picked the Night Sky and saw that it is 0.96 for Night Sky and only 0.73 for Monument which seems like a pretty decent improvement for a colour which would still give us the look we want as I think it would look a little boring with the walls and roof all white (or close to).
The builder says that the colour of the rood actually doesn't make that much difference to the temperature inside the house, especially with decent insulation in the ceiling. I would also be open to getting fans in the roof if it would help. The house is in Perth and less than a 1km to the beach so hopefully we will enjoy a decent sea breeze most afternoons and a good portion of the roof (maybe 30%) will be coated in solar panels anyway.
Happy to listen to any advice.
Phil
If you cant afford double glazing then the cheapest options are:
1. Anticon blanket
2. Get your entire house sarked and have them tape every single join in the sarking with insulation tape ( we do this and for a 2 story house it costs less then $2k)
3. Get them to fill every penetration with expandable foam
4. Put acoustic foam under the bottom plates of your external walls
5. Get them to seal the gap between the bottom plate and the slab with acoustic sealant
6. Invest in a decent set of roller blinds
This will stop the cold are escaping and hot air coming in. You should be able to all of that for under $12k
Cheers
Simeon
I appreciate your point but in reality this is false economy compared to double glazed windows....
Windows are like holes in the wall, or a better analogy is holes in the bottom of a boat. Yes, imagine holes in the bottom of a boat...
They take in water (analogy lose heat or gain heat), they do that regardless of the rest of the boat. You can seal other minor cracks and gaps to 100%, but your boat will still sink because the holes in the hull will continue to take in water at the same rate. There is nothing you can substitute for fixing these holes - nothing! You would be better off having say 30% of your windows double glazed than any improvement in batts or sarking. Curtains and blinds do make a difference, but if you have ever lived in the cold you would know that the difference is minimal.
Ed