iank
Member
We are going to build a new home shorlty. I think I have read too much info on types of insulation. If anyone has some recent information or practical thoughts please.
We are wondering what to use that is the best value per dollar to achieve an airtight home with R2.5 in the external timber frame and R6.0 in the ceiling.
thanks
David
Member
iank said:home with R2.5 in the external timber frame and R6.0 in the ceiling.
R2.5 is a joke no matter what any builder tells you "there is NO such thing as too much insulation"
Our house is designed with R10 in the ceiling and R6.0+ in all external walls, I'd make it higher in both if I could fit it in but I can't, therefore that's the limit I can do.
dlvb19
Member
Hi Ianc,
Search the archives, so much discussion on this topic.
In brief though....
Where are you building? Whats the climate like?
In general I agree with David, but at some point the heat savings are not worth the extra money invested in insulation. At that point the money would be better spent on solar panels or a more efficient RC-AC.
As a minimum I would go for R4 wall and floor and R6 ceiling.
efficient design
Member
If you're trying to build to passivehaus levels then it's difficult to beat SIPS as a fast, cost effective building system. SIPS are simple.... 
Consider 160mm SIP wall = R5.0
Investigate at http://www.superiorwalls.com.au
efficient design
Member
SIPS @ 350mm = R10,...still nice & simple construction, but I agree with dlvb19.....as R-value increases, payback benefits decrease significantly....it's about finding the balance of accepting the optimum R-value before diverting design investment into more aspects that have a superior payback & comfort value...as dlvd19 states.
efficient design
Member
Case in point:- Calgary, Canada....SIP exterior wall thickness @ 6.5" @ R5.3, SIP roof thickness @ 10.5" @ R7.72
http://www.titanwall.com/docs/Titan%20Wall%20Product%20Details.pdf
Where in Australia do we experience such extremes?....maybe Mawson in Antarctica.
It's about selecting the correct balance for YOUR climate zone & lifestyle.
Johnnojack
Member
David, what did you do to get R6 in the walls?
For a 90 mm stud wall, it is hard to achieve more than R = 2.5 (metric units).
To achieve higher R-values requires thicker walls or different construction. The extra expense comes there, not in the extra insulating material.
My 1998 house, with R=2.5 in the walls and R=3.5 in the ceiling, has proven high performance in a challenging climate.
The member posting as "efficient design" has avoided the trap of citing north american R-values in terms of antique (19th century) British Thermal Units. The web-site he links to does use them, though. Every newcomer to the topic deserves to be told that north american R-values are six times larger than ours. No website constructed in north america ever states that that is the case.
I, too would like to ask David how he achieved R=6+ in the walls.
iank
Member
Thanks for all the ideas
I am looking at standard 90mm framing and my understanding was physically that it wasnt possible to achive much better than R2.5 in that space.
Is it cost effective to use r2.5 and then additional styrene foil backed insulation board external to increase the R value?
I was aware of the usa R values being some 6 times the rating value than here.
I will have a look at the sip system but prefer to stay with a conventional frame system.
Is David confusing the usa/canadian rating system?
We are building on the Belarine peninsular near geelong in Vic.
I am interested in people who have practical recent experience in achieving a cost benefit solution. After all as dvlb says there must be a break even scenario spending more for less benefit.
efficient design
Member
An apology please Catopsilia, the R-values I quote ARE metric....I've been around long enough to know the difference....if I was quoting imperial it would be something like R-20 for the walls :roll:....the website I posted does have those 'extremely high' values....as I said, my R-values are metric so as to bring some relevance into the discussion where temperature ranges in Calagry range from <-30C to >30C & the metric R-values I've quoted are considered typical.
efficient design
Member
Oooops, a serious foot in mouth moment. Thanks Annette for pointing out my dyslexic slip. I see that Cato was actually keeping my back.....apologies to you sir:- keep up with your informative posts. ED
tailend
Member
iank said:
I am looking at standard 90mm framing and my understanding was physically that it wasnt possible to achive much better than R2.5 in that space.
When designing stud walls I built a spreadsheet model to calculate the actual R value delivered by a wall. If you put R2.5 bats in a stud wall and protect them from forced air movement (as a breeze can significantly reduce the insulation properties of bats), then they should deliver an R value of around 1.9 (best case) due to the heat being conducted around the bats by the wooden frame. The same happens in the roof. Interestingly, the higher the R value of the bats the worse the R value is compromised by the wooden frame. There are ways to combat this effect.
Ben1
Member
David said:
R2.5 is a joke no matter what any builder tells you "there is NO such thing as too much insulation"
No, but there is such a thing as diminishing returns. At some point, your ceiling insulation is going to reduce your rate of heat loss from 100 W to 50 W and your dollars will be more cost effectively spent reducing energy consumption in other ways (eg, a high performance heat pump or improved glazing).
David
Member
Ben1 said:
No, but there is such a thing as diminishing returns. At some point, your ceiling insulation is going to reduce your rate of heat loss from 100 W to 50 W and your dollars will be more cost effectively spent reducing energy consumption in other ways
I'd rather not have to input any power at night at all, having enough insulation of one form or another is still better than spending money on heating just to keep it (house) warm enough during the day there is typically plenty of heat generally from a number sources, that work on a very simple kiss system. R2.5 is still a joke for outer walls, while it might better than nothing it's still woefully inadequate.
efficient design
Member
Hi David,
For my own curiosity, & I guess the Forums, can you describe the construction layers.
Do you have a costing in $/m2 for the completed wall system?
ED
David
Member
The design is double metal frame system with a gap between them, all prefabricated frames in a factory and then transported to site, sits on a concrete slab, metal clad roof and walls, plaster board inside. there are the required permeable membrane/s around the outside, insulation, insulation, insulation, plasterboard.
efficient design
Member
Thanks David,
What did this equate to as far as $/m2 for finished (decorated) wall.
For my own knowledge, I'm trying to get an indication of how much people are prepared to pay for such construction.
Results will break down to a simple $/m2/R-value and the effect on net/gross floor area ratio
ED
Ben1
Member
David said:
I'd rather not have to input any power at night at all, having enough insulation of one form or another is still better than spending money on heating just to keep it (house) warm enough during the day there is typically plenty of heat generally from a number sources, that work on a very simple kiss system. R2.5 is still a joke for outer walls, while it might better than nothing it's still woefully inadequate.
What kind of windows do you have? By the way, where is the house located? Above the snowline?
David
Member
efficient design said:
What did this equate to as far as $/m2 for finished (decorated) wall.
Total cost for the house works out at about $10K per square metre completely finished, which includes, slab, water tanks, sewerage system, fixtures and fittings, kitchen fitted out, walk in pantry, all lighting, disabled accessible throughout, verandah front and back, bushfire protection system, other stuff of my own design, outside 6m x 6m coolroom, data cabling, various control systems, large off-grid system. 4 bedrooms, open plan living area, dining room, games room, home office/library, 2 bathrooms + 3rd toilet, all internal walls have insulation in them as well.
Ben1 said:
What kind of windows do you have? By the way, where is the house located?
Double Glazed Laminated Glass.
Shire of Strathbogie, near Violet Town (500M from the Hume Freeway/Highway).
** Edited 21-03-2016 Oh dear, not 10K I went back and looked about $1.1k per SQ metre 
If you get a contract builder to do it it could be as much as double in some cases.
Thanks for that valuable information, David.
efficient design
Member
Thanks David for sharing this information. It demonstrates a commitment to develop high performing homes that I'm sure will be with you for the rest of your life.
Yourself & 'tailend' at http://www.ata.org.au/forums/topic/46031 must be cut from the same cloth!
I only wish most of our clients were not so cost conscious & focused more on exceptional energy efficient design....but then that's the reality we deal with in business 
Eco
Member
David said:
Total cost for the house works out at about $10K per square metre completely finished.
Wow! Say a 200sqm house. Cost = 200x10k = $2000K = $2 million? It was a lot less than that for my 7 Star house - which was undoubtedly not up to the energy efficiency standards of David's house.
This topic, "Home insulation" is not restricted to low-budget homes. Most of us are stuck with low budgets; we seek maximum comfort at minimum cost. We know that cutting costs on insulation may lead to embarrassing expense for heating and cooling later on. We may take pride in finding innovative ways to achieve comfort cheaply.
It is clear from magazine articles, and from the kind of homes that typically win prizes for "Energy Efficient House of the Year", that some people who are motivated to aim for comfortable energy efficient living have budgets that are very large.
All ideas about home insulation are helpful.
David ,just as a matter of interest, what ,if anything,would you change if you did it all again ?
