Two walls Vs Q-con blocks

Air conditioning, fans, and anything related to keeping it cool, such as insulation. This would include any posts generally discussing how to keep it cool, such as which types of blocks are better insulators.... ideal wall thickness for keeping an A/C house cool, etc.

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walls

Postby cruzing » Fri Apr 04, 2008 7:54 pm

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Q!

Postby Rick B » Fri Apr 04, 2008 11:08 pm

An additional option is ProBlock, sold by HomeMart, as an inexpensive alternative to Q Con and Super Block. I used these blocks in my two-storey house and believe they will provide a cool house. Since I'm still constructing, I can't say for sure how good they are. But the house is noticably cooler already than the outside temperature. These blocks are 50x20x7cm and have a list price of 14 baht each (although I negotiated down to 12 baht a block). I used them only on the exterior walls. They are advertised to have only 1.5% less insulating capacity than the Super Blocks. One advantage they have over Super Block and Q Con is that they can be layed and rendered with normal cement; no need to buy a special adhesive.
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q-con

Postby cruzing » Sat Apr 05, 2008 9:11 am

One advantage they have over Super Block and Q Con is that they can be layed and rendered with normal cement; no need to buy a special adhesive.


That would be more convenient for sure. On http://en.wikipedia.org/wiki/Aerated_autoclaved_concrete it does state regular mortar can be used........"Even though regular cement mortar can be used, 98% of the buildings erected with AAC materials uses thin bed mortar, which comes to deployment in a thickness of 1/8 inch."

However, on this Australian website it states that there is some advantage to using thin bed mortar.
http://www.azom.com/details.asp?ArticleID=2163#_Thin-Bed_Mortar
How Does Thin-Bed Mortar Compare to Conventional Mortar?

The move to a polymer modified thin-bed mortar has increased the bond strength and overall masonry strength whilst at the same time reducing the volume of materials handling and storage on site. To lay 1000 standard bricks, 1 tonne of sand and 160 kg of cement are required. In contrast, to lay 1000 Slick Bricks, only 150kg of mixed thin-bed mortar is needed, significantly reducing the quantity of material needed on site.

IMO if you aren't into double walls, using any of the AAC blocks in your building project can only improve the comfort level of your home...the second best thing is double glazed windows and good roof ventilation.

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Postby tung » Sat Apr 05, 2008 9:54 pm

I am thinking of using an aac type block but am concerned about what thickness of block to use as I prefer not to go double skin. Many have used the 7.5 cm blocks but that seems to be a very thin external wall especially when you need to embed wire/pipe channels in them.

Am I wrong in thinking that a 7.5mm wall is too thin?
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Postby cruzing » Sat Apr 05, 2008 10:59 pm

tung wrote:I am thinking of using an aac type block but am concerned about what thickness of block to use as I prefer not to go double skin. Many have used the 7.5 cm blocks but that seems to be a very thin external wall especially when you need to embed wire/pipe channels in them.

Am I wrong in thinking that a 7.5mm wall is too thin?


IMO way too thin. The only blocks I've seen that I would think about using are at least 7.5 INCHES to 8 inches (approx 18-20 cm) around 46 +/- cm long and height at least the same as width or possibly more.

Even if we were doing a double wall of thin q-con, I think we'd want the external wall thicker than 7.5cm. As I said though just my opinion.

Attila used the some of the bigger q-con blocks. You could pick his brain for some answers.

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Postby dozer » Sun Apr 06, 2008 9:13 pm

Things have a habit here of being reduced to the 'minimum' to get a price point that will have appeal to the mass market. I would suggest the 20 cm thick blocks, even though they seem expensive it will be a minimal cost factor in the overall build. To be load bearing you would need more than the 7.5 cm. The 7.5 cm can be used as an alternate to the normal cinder block to fill in the gaps between the foundation columns but the insulative value of the blocks is reduced.
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Postby Khun Jean » Tue Apr 08, 2008 6:31 pm

I was thinking about thermal mass and how to use it.
Would a thin outer wall (7.5cm Q-con) and an at least 20cm thick concrete innerwall be efficient in a bedroom for instance where an aircon will be used. The thick innerwall would be cooler than the outer walls and will help to take the heat out of the room.
If you run the aircon at night, the wall will be cooled down and when it gets daytime this 'coolness' will be used to cool the room.

Opinions please. :)
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Postby Attila » Thu Jun 12, 2008 12:37 pm

Khun Jean wrote:I was thinking about thermal mass and how to use it.
Would a thin outer wall (7.5cm Q-con) and an at least 20cm thick concrete innerwall be efficient in a bedroom for instance where an aircon will be used. The thick innerwall would be cooler than the outer walls and will help to take the heat out of the room.
If you run the aircon at night, the wall will be cooled down and when it gets daytime this 'coolness' will be used to cool the room.

Opinions please. :)


Hi Khun Jean,

yeah, that is a good concept, and will have a good effect. You might even be able to optimize it with a cavity between the 2 walls and filling in some insulation material in it.
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Postby tung » Thu Jun 12, 2008 7:18 pm

Attila wrote:
Khun Jean wrote:I was thinking about thermal mass and how to use it.
Would a thin outer wall (7.5cm Q-con) and an at least 20cm thick concrete innerwall be efficient in a bedroom for instance where an aircon will be used. The thick innerwall would be cooler than the outer walls and will help to take the heat out of the room.
If you run the aircon at night, the wall will be cooled down and when it gets daytime this 'coolness' will be used to cool the room.

Opinions please. :)


Hi Khun Jean,

yeah, that is a good concept, and will have a good effect. You might even be able to optimize it with a cavity between the 2 walls and filling in some insulation material in it.


That makes about 27.5 cm not including the cavity insulation mentioned. Would that thickness be enough to hide the inner shape of the concrete columns?
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Postby Attila » Thu Jun 12, 2008 8:51 pm

tung wrote:
Attila wrote:
Khun Jean wrote:I was thinking about thermal mass and how to use it.
Would a thin outer wall (7.5cm Q-con) and an at least 20cm thick concrete innerwall be efficient in a bedroom for instance where an aircon will be used. The thick innerwall would be cooler than the outer walls and will help to take the heat out of the room.
If you run the aircon at night, the wall will be cooled down and when it gets daytime this 'coolness' will be used to cool the room.

Opinions please. :)


Hi Khun Jean,

yeah, that is a good concept, and will have a good effect. You might even be able to optimize it with a cavity between the 2 walls and filling in some insulation material in it.


That makes about 27.5 cm not including the cavity insulation mentioned. Would that thickness be enough to hide the inner shape of the concrete columns?


Yes, that should be enough. However with a 20 cm thick concrete wall, as Khun Jean proposed, you do not really need these concrete columns anymore.
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Postby chiangmaiexpat » Fri Jun 13, 2008 8:54 am

Are you trying to build a bomb shelter? :D

Cheers, CMX
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Postby Attila » Fri Jun 13, 2008 11:34 am

If you don't need the loadbearing function you could also get a nice thermal mass with a clay brick wall. I've seen that recently and it was, to my surprise, free of the smells I always associated with clay walls.
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Postby Jack » Fri Jun 13, 2008 5:38 pm

Are you really gaining anything with the thermal mass idea if you have to pay for the cooling? Generally this is advantageous when you live in a climate with hot days and cold nights so you get the cooling for free. It seems like it'd be more cost effective just to insulate well and run the aircon during the times when you want the rooms cool. Otherwise the aircon going to have to work a long time every night to cool the walls down and then you might not even be there the next day to enjoy it. And recovering the coolness from the walls won't be 100% efficient so you'll be losing something from that as well.
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Postby Attila » Fri Jun 13, 2008 7:05 pm

Jack wrote:Are you really gaining anything with the thermal mass idea if you have to pay for the cooling? Generally this is advantageous when you live in a climate with hot days and cold nights so you get the cooling for free. It seems like it'd be more cost effective just to insulate well and run the aircon during the times when you want the rooms cool. Otherwise the aircon going to have to work a long time every night to cool the walls down and then you might not even be there the next day to enjoy it. And recovering the coolness from the walls won't be 100% efficient so you'll be losing something from that as well.


There can be a nice gain if you consider that you could have the smallest available a/c unit running only, which will run longer but using less power overall.

As your comment implies the real gain you will get if you cool that thermal mass with free or almost free energy. You could use cool night air or ground water and pipe it through that thermal mass constantly, removing heat slowly but steadily. This is the idea of thermo-active building components, as described here: http://siamgpi.com/solarpower/thermo-ac ... nents.html
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Postby tung » Fri Jun 13, 2008 7:29 pm

cruzing wrote:
tung wrote:I am thinking of using an aac type block but am concerned about what thickness of block to use as I prefer not to go double skin. Many have used the 7.5 cm blocks but that seems to be a very thin external wall especially when you need to embed wire/pipe channels in them.

Am I wrong in thinking that a 7.5mm wall is too thin?


IMO way too thin. The only blocks I've seen that I would think about using are at least 7.5 INCHES to 8 inches (approx 18-20 cm) around 46 +/- cm long and height at least the same as width or possibly more.

Even if we were doing a double wall of thin q-con, I think we'd want the external wall thicker than 7.5cm. As I said though just my opinion.

Attila used the some of the bigger q-con blocks. You could pick his brain for some answers.

cruzing


Attila

I believe that you used quite a thick AAC block on your build; what thickness block did you use, qcon or superblock. How do you rate the coolness of your house and lastly do you reckon your leccy bills have been reduced.

Cheers

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