Insulation - Which R Rating?

Hi All,

I am just wondering if anyone has advice for R ratings? I have a friend at TAFE studying architecture and she was taught that a higher R rating is not better, that it depends on the area.

She was saying for Newcastle area, a R2.5 is better than 3.5 as a 3.5 will not allow the heat to flow properly, therefore in winter the heat will not stay in...or was it in summer..which ever way it was, they were taught that it's not a matter of getting the biggest number, it's suiting to the climate.

The difference is, all of the people I talk to for the government grant say 3.5 is better. Apparently 3.5 is cheaper, is that why it's "better"? cause they get more money out of it?

Cheers
Chris
 
3.5 is more standard, more common, installers already have a shed full of the stuff waiting to go. You want something different, they grumble and complain and have to go out of their way to get it for you - or talk you into buying what is already in stock or easy to get (go into a hardware store and see what they have in stock - it'll be the same).

Nothing wrong with 3.5 anyway :p
 
Heck no, I'm in (well, just moved from) a zone where you want to stick R5 on everything to keep the arctic -20 degree winter out. We have Canberra weather. R3.5 is actually compulsary on new builds here, which I'd say means that if you can track down whatever legislation that says put X insulation minimum on new builds, it'll say what is minimum in Newcastle.

I was just told this by a builder (it adds about $2500 to the cost of a new house, for me) so I have no idea what legislation they are citing.
 
Thanks Amy, that suggests what my friend says - Sydney (close enough to Newcastle) is 1.5-3, not 3.5 which they are recomending!

not only that, the government says 3.5.

haha. so do i just get the 3.5 and trust the government or pay for the 2.5?

chuckle.
 
3.5 is better than 2.5 is better than 1.5 is better than 0.

Different climates benefit differently from insulation for different purposes. Do you have a Queenslander on stilts in Cairns, keep the windows open and use fans for ventilation etc? Not a lot of benefit to be had from insulation there. But if you have a brick box in the same climate and run the aircon 24/7 during summer then i would suggest you need as much insulation as possible! Likewise if you live in Hobart - the more insulation the better...

The suitability of insulation thickness generally referred to is based on a cost / benefit analysis generally. For example, using 3.5 in Perth is generally considered to be overkill although it is still better than 2.5 provided that you can open all your windows effectively when the sea breeze arrives... otherwise it will trap the summer heat in over consecutive days. The grant skews the analysis though IMO so I put in 3.5 just coz it's better even though I may not notice the improvement!

Main thing is though if you generally use a/c (heating or cooling) then the more insulation the better! Just like your fridge in that respect...
 
check http://www.environment.gov.au/energyefficiency/publications/index.html#climate - there are climate maps that determine which R rating suits your area.

this is the recommended R rating under the govt. scheme - don't believe a word you have been told by installers etc. trying to flog product...or even architecture folks for that matter - there is a real science involved in this stuff...a higher R rating doesn't mean better - it depends on your climate!!

it is that simple.
 
it is a bloody good question and i know exactly what you mean, but i do not have an answer, ??/
if the place is fully insulated and you use air cond its a different story,
but keeping the heat in as long as you can would also mean keeping it out on hot days , providing the windows are closed and covered,
 
check http://www.environment.gov.au/energyefficiency/publications/index.html#climate - there are climate maps that determine which R rating suits your area.

this is the recommended R rating under the govt. scheme - don't believe a word you have been told by installers etc. trying to flog product...or even architecture folks for that matter - there is a real science involved in this stuff...a higher R rating doesn't mean better - it depends on your climate!!

it is that simple.
That's actually incorrect. R3.5 is the minimum requirement in the BCA which is why it is being specified as the standard.

To the OP - Your friend is getting confused between R rating and other methods of measuring heat transference. As far as your ceiling goes, you want the highest R rating possible in ALL applications. R3.5 glass batts are probably the best as far as providing value for money vs efficiency. The diffence between R3.5 and R4.0 or R4.5 is minimal when it comes to heat transfer which is why R3.5 is optimal.

When considering materials for walls, floors etc... that's where the highest R rating isn't always best.
 
The mob I am using are putting these in. Silver-Batts up to 240% more-effective
When Silver Batts were tested at Australian Institute of Tropical Architecture, James Cook University, Townsville, they prevented 100% heat flow down. They didn’t just slow it down, they completely eliminated it.

What makes Silver Batts an effective insulation for Australia’s harsh climate is not just the layers of foil, but the 50mm air cap between the foil.

The design of air combined with foil has given Silver Batts the highest “R” value in insulation. The value is up to R6.5. That’s up to 240% more effective than other types of insulation.

The “R” value is the standard measurement of thermal resistance. It measures how well insulation reduces heat. The higher the “R” value the better the insulation.

Silver Batts, available from Insulation Super Store come with a lifetime warranty, have the best possible fire rating and are approved by the asthma foundation of Victoria.
 
That's actually incorrect. R3.5 is the minimum requirement in the BCA which is why it is being specified as the standard.

not incorrect - the BCA standard only applies to new homes and homes constructed after 2003. See section four - table 1 of the following link after you have determined your climate zone:

http://www.environment.gov.au/energyefficiency/insulation/homeowners/guidelines.html#five


also http://www.insulco.com.au/INSULCO/INSULCO/RESOURCES/DOCUMENTS/Zones.pdf

for example, here in South East Queensland R3 is the recommended. Hence, that is what is quoted by most companies and the area per square metre covered by the rebate is higher than some other areas such as Perth which requires the use of r3.5.
 
Well, I had 3.5 put in my ceiling (thanks Kevin) and it seems pretty good.

I'm not really up on all the R stuff, but I reckon the difference between no insulation and some insulation is pretty significant.

The difference between 2.5 and 3.5? I'm not sure I would notice it.

Scott
 
Go check out "Yongala" on the meteorology website. It holds pretty much all the SA records for coldness :eek:

.. which never stops the thermometer hanging on the shed registering -20 sometimes when the BOM says it was a toasty -10. Also means whenever we go visit balmy, sundrenched Adelaide in winter the in-laws offer us a million thick blankets and we're sweating in T-shirts ... no really, if we say we're not cold, we're NOT COLD.

ETA: averages...
http://www.bom.gov.au/climate/averages/tables/cw_019062.shtml

Couldn't find the pages with all the record extremes on it ..
 
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