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Best Building for hot area, Your opinions

PostPosted: Sun Jan 05, 2014 7:52 pm
by treechange
Hi Guys we are planning to build a house near Coona NSW 2395. This area can and does get rather hot. I am looking for ideas of building a house that will keep us cool during these hot days, any materials that you have used that you consider are worth talking about.

I know double brick, straw bail (maybe, not sure) is ok, but are the better ways of keeping your home cool while its hitting 40 something out side.

So what are your thoughts, do you have experience in something that works.

I can build any way I like (within bush fire regs), and want to have an extremely comfortable house.

Thanks Nig :)

Re: Best Building for hot area, Your opinions

PostPosted: Sun Jan 05, 2014 8:01 pm
by davidg
treechange wrote:Hi Guys we are planning to build a house near Coona NSW 2395. This area can and does get rather hot.

How big is the property ?

Re: Best Building for hot area, Your opinions

PostPosted: Sun Jan 05, 2014 8:06 pm
by treechange
2.5 hcrs heavily wooded, flat.

Thanks

Re: Best Building for hot area, Your opinions

PostPosted: Mon Jan 06, 2014 2:11 pm
by Warpspeed
Many very effective things you can do.

The old original traditional Australian Homestead (with its classic pyramid corrugated tin roof, and southern cross windmill...) had a very wide veranda running all the way around which kept the sun completely off the walls during most of the hottest part of the day which was (and is) pretty effective.
Even if its not a proper verandah, extend the eaves well out on at least the northern side of the house.
You (or your architect) can work this out from latitude and sun angles, so that the northern wall remains in complete shade over all the mid summer months.

Next "must have" is a very efficient under roof ventillation system. Vent all that hot air right away, so that the ceiling insulation has far less heat load. You can do it with a cupola, or even those rotating wind powered exhaust fans installed right along the apex of the roof. You simply cannot have enough roof ventillation.

There may be problems in heavily timbered bush fire prone areas, but if you can...
Plant some desiduous shade trees very close to, and around the house, particularly north and west. The falling leaves are a nuisance, but you will have good summer shade, and after the leaves shed in autumn, you will get the benefit of a much more friendly winter sun.
Native Aussie trees are not up to the job.
You need European desiduous trees that have broad lush green leaves in summer.

There are arguments for and against high thermal mass construction.
If you live very near the coast with less extreme fluctuations in temperature, low thermal mass can be much easier to heat and cool.
If you are located well inland, with scorching hot days and freezing cold nights, high thermal mass construction can help to even things out.
But once all those bricks and concrete heat up, you are going to need some pretty potent airconditioning to maintain a good comfort level.
Difficult to say, it depends where you are.

One last tip. There is some pretty tricky high tech window glass available.
High rise city buildings with enormous almost total glass areas all use it.
It looks like a mirror from the outside, either silver or bronze, it reflects both UV and deep infrared, hugely reducing solar heat gains. But also very importantly it also reduces the UV glare when looking out from the inside. It also offers complete privacy during daylight hours.
Its really good stuff, but rather more expensive than ordinary clear window glass.
You probably dont need it on the southern side.
I fitted some to a bedroom that faces due west, and it made a very significant improvement to heat gains in late summer afternoons.
One brand I am familiar with trades under the name of "solar cool". There are others, but I suggest you do your own research into this
Its terrific stuff, particularly on the western wall that may suffer from late afternoon direct sun.

Re: Best Building for hot area, Your opinions

PostPosted: Tue Jan 07, 2014 7:38 pm
by treechange
ok so we have decided .

Straw bale, lime rendered. 3.0m wide veranda all the way round.

Not much else to say, blanket under the iron, r4 batts in the ceiling, and a few whirly birds on the roof. No shade trees, I would rather put 7kw PV system and aircond.

seeya :D

Re: Best Building for hot area, Your opinions

PostPosted: Fri Jan 10, 2014 9:18 am
by jimbo
Just make sure that the 3m veranda doesn't shade the windows of winter sun

Re: Best Building for hot area, Your opinions

PostPosted: Fri Jan 10, 2014 9:46 am
by Alex Morrow
(South east Queensland here, with some hot summer days - 42° on the southern wall of the house, in the shade, last Saturday, 45° in the uninsulated shed)
When we were building, Kentucky log homes were all the rage. We told our architect friend we wanted 6 foot verandahs all around. No, you don't, he told us; you want 3 metre verandahs on the north and the east. He was dead right.
In winter, the northern verandah gets plenty of sunlight, and the table there is perfect for morning tea. We built a tall "carport" between the house and shed on the southern side, with roof overlapping both house and shed. The south, under the very tall "Elephant House" is now the best place in summer, provided it's not too hot. When it is hot, we close all the windows of the house, and let the insulation in the roof and the thermal mass of the concrete floor do their thing, and in the 42° referred to above, it wouldn't have been above 35° in the house - hot, but not uncomfortably so.
We do get afternoon sun on the western brick wall, but shrubs planted there have reduced the heat at that end of the house.

Alex