Browse Forums Heating, Cooling & Insulation 1 Jul 20, 2011 9:38 pm Hi all I've been searching around for information on insulation in the tropics for a while, and it's pretty hard to come by. Most folks live south of Darwin, and are mostly interested in the dual aims of keeping cool in summer, warm in winter. Up here, there's not a single house with any form of heating in it, and for over 6 months of the year it is sweltering hot and extremely humid! I'd welcome any thoughts on these questions: I'm building my first home in Darwin from two shipping containers. I'm going to clad the outside with corrugated iron, and line the inside with plasterboard. The original 3mm sheet steel shipping container wall will be between these two layers. Generally it seems to be the consensus that up here, you want to avoid bulk insulation, since you want the house to readily give up its heat in the evening. Brick-built houses are a disaster - long into the evening, it's much more comfortable to be outside, even if you are being attacked by mosquitos! However, I plan to have air conditioning, so I obviously want to keep the cool air inside. My original plan was to lay up the walls like this: corrugated-iron : sisalation foil wrap : 3mm steel wall : insulbreak 65 : plasterboard. However, someone suggested doing corrugated-iron : insulbreak 65 : 3mm steel wall : air : plasterboard. With the first option, will the foil wrap be enough to prevent the steel wall from heating up underneath the corrugated iron? Does the layup plan make sense? Is there enough bulk to keep the cool air inside? How is a normal steel-frame house insulated in the tropics? Any and all thoughts gratefully received. cheers Biz Re: Insulation in the tropics 2Jul 20, 2011 10:52 pm I think the sisalation won't make much difference to how the container steel heats up. There info about Basic Insulation here http://www.anewhouse.com.au/?cat=21 including some idea of how reflective sisalatation performs. I think the issue about reflective insulation cooling better than bulk is just the manufacturers confusing the issue that their insulation performs better one way rather than the other. if you are using reflective it needs layers of still air to work well Sisalation by itself will have minimal effect. My view is its best to keep the inside cool by well insulated walls with a high total R value. When the outside temperature cools then open (fly screened) windows to cool the inside. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Insulation in the tropics 3Jul 22, 2011 10:26 pm there are two possible ways to go: The first is, like said above to insulate a box really well to not to get much heat in. I would still look for sufficient ventilation, putting the windows in were you can get draft through the whole house and I would not use sliding windows because they don't give you enough insulation. My old neighbour in Brisbane had to put AC in after changing his old louvre windows to aluminum sliding ones. The second method is the more traditional approach to build a drafty shack. That is what the Queensland houses are about: on stumps to get ventilation from underneath, leaky floorboards, and drafty walls. the same priciples can be found in SE Asian houses. We had a house like this and it worked very well without AC. But it is important to plan good shade trees around, this makes a big difference. Re: Insulation in the tropics 4Aug 23, 2011 1:00 am Sisalation will block > 99% of radiant heat which is the main source of heating during the day. As mentioned, good shading of walls and roof by tall trees help significantly as radiant barriers as well. Re: Insulation in the tropics 5Aug 23, 2011 9:11 am Reflective foil only works if there is an air gap on either side of it. both sides is even better. Reflective foil without an air gap is the same as no foil at all. Air gaps are good generaly, even if there is no foil. I would go for maximum insulation and ventilation. The ventilation does not have to be windows - opaque louvres would work. This way at night when the temperature outside is less than the temperature inside you can ventilate. Make sure you have ventilation at each side so you get good cross flow (north and south would be good, but make sure the north has overhang and the south can be closed off (blockout shutters or similar)). Demolition August 2009, Construction Started September 2009, Completed December 2010 Re: Insulation in the tropics 6Aug 23, 2011 10:29 am When attaching the iron, put some battens down to create an air gap and then line with foil then your cladding. This will also create a chimney effect where air constantly cools the gap between the cladding and the container wall. I am saying that double brick has similar thermal performance due to thermal mass effect. It will be still very interesting to see the state of your framing after 10-15… 10 23170 Hey guys building a new place through a volume builder and just wondering if i should complain to the site supervisor as we just had plasterboard installed. Looks like… 0 8927 1000000% definitely add insulation. I have in my home and it makes a big difference minimising sound transfer. Insulation is pretty cheap and definitely worth it 2 3665 |