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Heat Insulation Canvas

03/22/2012 11:06 PM

I live on the West Coast of Australia and the summer temperatures range between 30 to 40 C.

My bedroom is on the west side of the house and has large sliding glass windows.

Whilst they are covered in curtains with insulated backings and also have external canvas awnings, the room still becomes unbearably hot

Can anybody recommend a covering/paint/coating to the canvas awning that would repel/reflect/block the heat transmitting to the glass??

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#1

Re: Heat Insulation Canvas

03/22/2012 11:11 PM

How is the rest of the wall constructed?

Insulation?

Roof?

More detail.

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#2

Re: Heat Insulation Canvas

03/23/2012 3:42 AM

As to my knowledge the houses in West Australia are built rather unsophisticated. You will find that when you answer Lyn's question that it is not only the window but the rest of the house structure that matters. Curtains in the inside will not prevent the heat from entering the house. The best help is a shading from the outside. Look at window shutters or awnings.

Or plant a decisious tree. This will let the sun in in the Wintertime.

If you check the rest of the house structure look for double wall or singel wall, air slots on the footings of the wall being open and not blocked and if the hot air can escape into the roove cavity or elsewhere. Is there insulation in the ceiling?

Good luck

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#3

Re: Heat Insulation Canvas

03/23/2012 7:33 AM

30 to 40 C is equivalent to 80 to 104 F

Quite typical temperatures.

1. Assuming you have an attic, removing the hot air from there with a fan would help.

2. Having fans providing air movement inside the hose would help.

3. Having fans blowing the hot inside air out would help.

4. Having fans blowing the cool evening air into the house would help.

5. Keep the curtains closed while the sun is shining on them would help.

6. As IdeaSmith stated having some trees to provide shade on the house during the hottest part of the day will help.

7. Even with those items you probably need an air conditioner.

8. When you are home during the daytime, get cool air inside the house during the morning and then close the windows, draw the shades during the heat of the day. It works for us.

Our house has large windows facing the west with large windows. We enjoy the view over the lake but the house does heat up in the summer time.

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#6
In reply to #3

Re: Heat Insulation Canvas

03/23/2012 11:40 PM

"Assuming you have an attic, removing the hot air from there with a fan would help." Far more effective is reflective insulation - properly installed it can reflect heat over 95%. But I would guess you have it in the ceiling already - Have you got an IR thermometer? You can identify the heat source, it may be through the walls as the sun gets low. You can get an IR thermometer on ebay or maybe borrow one for a few days. Also looking for a good material for canopy / awnings - let me know if you find one. My summer is much sooner than yours -

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#4

Re: Heat Insulation Canvas

03/23/2012 6:00 PM

There is an Australian company "Coolaroo", we use them with great success, "mounted outside" to help block UV

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#9
In reply to #4

Re: Heat Insulation Canvas

03/24/2012 5:04 AM

I hope you mean IR

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#5

Re: Heat Insulation Canvas

03/23/2012 11:23 PM

"a covering/paint/coating to the canvas awning"

Your question is very well chosen. Canvas awnings are commonly very stupidly designed. They often are striped or of uniform dark color on the top, when they really should be as reflective as possible. Bright white is OK, but reflective foil laminated onto the top is better.

The fabric support should be of substantial thickness and preferably plastic impregnated to prevent the interstitial voids being uselessly open. Open voids transfer the absorbed surface heat (i.e. the unreflected portion) to the underside. An alternative successful core is a heavy-gauge non-woven "fluffy" fabric.

The underside of the awning should be non-radiative: it should be of light color.

If the chosen awning composite fabric conforms to those three rules, the awning performance will be optimized. There is a material faced with aluminized Tedlar film, whose body is a fluffy white non-woven "blanket", all made stretch-free with an included glassfiber scrim, used in aerospace fabrication. It is perfect for awnings but never used for that application!

Why? Because the neighbors would complain about bright reflections and an unattractive streetscape. If you have no neighbors, go for it!

Mark Bingham
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#7

Re: Heat Insulation Canvas

03/24/2012 12:27 AM

There is a new glass available that has a sun reflective character. It was developed to keep carpeting from fading when the sun shown through the window. It is available in the U.S. in a double pane window that keeps the heat out so your air conditioning system doesn't cost an arm and a leg. It has been on the market in the U.S. for years. Check it out.

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#10
In reply to #7

Re: Heat Insulation Canvas

03/24/2012 5:09 AM

Yes, every house in a hot. Climate should use these windows. They are usually called "low solar gain" windows or similar. The principal is that they have a selective coating that reflects the infrared (IR) range from the sun. This range is invisible to the eye so the coating does not alter your visual perception (the window still looks clear). However because almost 50% of the sun's energy is transmitted in the IR range, thee coatings can prevent a lot of heat getting into the house.

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#8

Re: Heat Insulation Canvas

03/24/2012 3:44 AM

In the Queensland outback, they use evaporative coolers that are mounted on top of the roof. They run water thru canvas and a fan sucks thru the wet canvas and blows down into the house, thus improving temperature and humidity. The air is forced out of the house, so hot air can't come in. If I remember OK, one maker is Bonaire. I will check and get back to you.

They should have them over your way.

You could try the old Coolgardie safe arrangement yourself. Hang canvas in a tray of water and blow air thru it. Cools just like the old canvas waterbag on a car.

Aliter, hang up sisalation (ceiling insulation), two lines of it, space between them, with the shiny side facing the sunny side.

Use fans to blow air out of the house towards the sun, and suck in fresh air from the other side of the house.

I live in Brisbane. Summer, I open the house during the night and shut it up tight during the hottest part of the day. Luckily I have 3 feet of eaves overhang, so the sun can't shine in a fair part of the day. The house is always 4C lower than outside. If I put in double glazing (large windows) and insulated the walls (weatherboard) I should do better.

Plant lots of trees on the sunny side, close together. Lillipilli gives fantastic shade (my grass won't grow under it), grows quickly to 15 or 20 feet, but it drops lots of leaf litter.

Is your ceiling adequately insulated? Before I did mine with R3.5 glassfibre batts (~U0.3), I had your problem with excessive heating.

Maybe a Victorian could give us a few tips. Houses are better designed down there for a large range of temperature (0c to 40C is possible).

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#11

Re: Heat Insulation Canvas

03/24/2012 12:37 PM

Lots of good ideas here already and you need to solve all the areas where heat is getting into the house, not just one, but maybe one at a time......

Although we don't often have such high temperatures here in Germany, we often get above 36°C in summer. We had wall insulation added on outside the house shortly after replacing all the windows with modern double glazing (the old double glazing ones were over 40 years old....) 10cm of insulation was added, today I would add even more, 15cm at least is the common value used today. It was only recommended to be 6cm in 2008.

Some people have asked us where the air conditioning is, they are surprised when I say we don't have one running - we do have one but haven't needed it since the house was insulated properly....its a small portable unit only that could not cool the whole house, one room only.....

I hope this helps.

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#12

Re: Heat Insulation Canvas

03/24/2012 3:21 PM

The material used for sunshades in autos is really good for stopping the sun. I used it under the convertible top of my car, it made a really big difference. The two layers of reflective plastic quilted with air pockets makes a good insulator. This material may be available in sheets, I'll check.

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#13

Re: Heat Insulation Canvas

03/24/2012 9:35 PM

Thanks heaps to Mike K who came up with the material that Relativity K referred to. So Relativity K, once I cover the outside facing side of the awning with the reflective material, should I also paint the underside of the awning (Yes it is striped) a dark colour to absorb any heat that many have been radiated through the fabrics or should I paint it bright white (or cream for my eyes) on the underside to reflect any heated air in the space between the awning and the glass door??

Thanks heaps everybody for your comments

Therese

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#14
In reply to #13

Re: Heat Insulation Canvas

03/25/2012 12:06 PM

Black is a Bad idea if it is exposed to sunlight and you want to stay cool. This is because black means all visible light has been absorbed and consequently turned to heat. For an interface where there is no sunlight however, we can not make such a statement because instead of visible light, you are looking at heat radiation which is infrared somewhere in the 10micrometer wavelength range. Because it is not visible to the eye, we can not say that a back color will also absorb infrared. Anyway, you should be looking for something that reflects infrared. Aluminum does that fairly well, that's why you often find insulation materials like glass mats with an optional Aluminum foil on one side. By the way, it is always better to fill gaps with insulating material than to leave large air gaps even though air has a low conductivity. When air can move around convection patterns form which increase the heat transfer through the gap way over the conductive heat transfer.

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#15

Re: Heat Insulation Canvas

03/25/2012 5:02 PM

Create shade were and if you can!

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#16

Re: Heat Insulation Canvas

03/25/2012 10:31 PM

What latitude is your house, Therese?

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#17
In reply to #16

Re: Heat Insulation Canvas

03/28/2012 3:50 AM

Hi Stuart

Latitude 31° 60'S - Longitude 115° 50' E

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Andy Germany (1); Byron Jay (1); ddk (1); IdeaSmith (1); JWthetech (1); ky (1); lyn (1); mike k (1); Phaddy (1); Relativity PL (1); Stuart21 (2); theresejulianna (2); Tompa (3)

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