# Ceiling Insulation



## Julia (8 May 2009)

I'd appreciate any comments from people who have insulation installed, e.g. 

1.  what kind and why did you choose that type?

2.  how effective have you found it?

3.  is the effectiveness more noticeable in terms of reducing heat in summer or 
    holding heat inside in winter?

Any particular things to look out for?

With thanks.


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## glads262 (8 May 2009)

Julia said:


> I'd appreciate any comments from people who have insulation installed, e.g.
> 
> 1.  what kind and why did you choose that type?
> 
> ...




Hi Julia,
I am in a rented house, newly built - so don't know exactly what type of insulation is in place, but I know that all walls and roof are insulated.

In winter (average 18 degree day) - we only use our heater on days when there is rain - if we can get some sunlight in the windows during the day, this heats the house to 21 degrees. By 6 oclock, cooking tea is enough to boost the temp and keep it around 21 degrees. By morning the house is usually back to 19 degrees.

So the effect is huge in winter - but if you don't get heat during the day from the sun, or cooking, you will need to use your heater to get the temp up initially.

In Summer - you basically start your aircon up later. On a 40 degree day, usually you would have to turn your aircon on the second you get up. With insulation, you can usually last until about 3pm before it gets above 25 degrees inside. So you still use the aircon full on, but for less time overall.

Hope this helps!


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## moXJO (8 May 2009)

tile or tin on your roof? 
Is roof newish?


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## Julia (8 May 2009)

glads, thank you.  Yes, really helpful, thank you.

moXJO, tile, 16 years old.


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## jackson8 (8 May 2009)

Julia said:


> I'd appreciate any comments from people who have insulation installed, e.g.
> 
> 1.  what kind and why did you choose that type?
> 
> ...




hi julia

being a ceiling fixer all of 33 years i would go with nothing less than a fibreglass batt
most would recommend a R  3.5 rating for ceilings
will help both ways to keep heat or cold out and keep your cooling or heating system in
it is cost efficient and fire resistant

forget blow in as imo it is absolute c**p messy and can smoulder in the event of fire
natural fibres are too expensive ; such as wool batts and i wouldnt recommend polyester either

will depend on how easy it is to access your ceiling space

hope this helps
gary


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## Julia (8 May 2009)

Gary, thank you.   Why are you opposed to the polyester?


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## awg (8 May 2009)

My observation is to do with insulation effects in summer.

I recently had my walls clad, in a highly insulative material.

It was the right stuff for the job, but the insulation was only secondary.

I have found that it is actually a "heat trap" in the summer evenings, as I suspected it would be, which means more aircon on hot nights.

I do expect to save big in winter though

When I first questioned the salesperson about the summer heat trap, he denied it at first, but started mumbling when I asked further.

Passive Solar design is an interest of mine, and makes a huge difference.
Unfortunately, my home has very poor passive solar design, as do most homes.

ps Julia..I reckon you should read every single page of that BEPPA thread...


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## Julia (8 May 2009)

awg, I'm only considering doing the ceiling, and then only because I'm don't have to pay for it.  The house is pretty comfortable in summer but does need heating in winter.

The point you raise is one I've been thinking about, and I find it hard to see how if heat is going to be pleasantly trapped in during winter, why isn't it similarly going to be trapped in summer?


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## moXJO (8 May 2009)

Julia said:


> awg, I'm only considering doing the ceiling, and then only because I'm don't have to pay for it.  The house is pretty comfortable in summer but does need heating in winter.
> 
> The point you raise is one I've been thinking about, and I find it hard to see how if heat is going to be pleasantly trapped in during winter, why isn't it similarly going to be trapped in summer?




With a tile roof in summer the roof space heats up a fair bit. Thus having a barrier between ceiling and roof space will prevent a lot of the heat transfer. It makes it worse if you tiles are not sarked underneath (foil backed paper).
During winter I suppose it works the opposite with the heat being trapped inside a little bit more. Having a lot of windows and areas that heat can escape or enter is something else you should take into consideration (north facing windows, large gaps round doors etc).

Depends on the area you live too


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## awg (8 May 2009)

the heat trap issue is affected by several variables.

including, the mode of heat entry into the house, its materials, orientation and roof/ceiling/wall characteristics.

concentrating on the roof, prevention of heat ingress in the day is good, but IMO, on hot summer nights, simple physics demand that heat will be trapped, therefore, your house will cool down much slower on very hot nights.

It has proven to be the case here.

I have fully deducted aircon, and spoilt teenagers who demand aircon at night if it is too hot

If anyone can convince you (or me), that you wont be hotter on a hot summer night, well I would like to hear how that can be.

Surprise, Surprise, they never mention this issue on the TV ads

Winter should save money.

Some people cant stand hot nights, if you have no aircon, to be borne in mind 

pps BEPPA profits today alone payed my cladding bill several times over


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## AlterEgo (8 May 2009)

Julia said:


> I find it hard to see how if heat is going to be pleasantly trapped in during winter, why isn't it similarly going to be trapped in summer?




To some extent it does. What the insulation basically does is to slow the heating and cooling of the house, and reduce the temp extremes. I've noticed this after I insulated my roof. ie. The house takes longer to heat up, so the air-con only needs to be turned on later in the day during summer, BUT once heated it takes longer to cool down as well. So in summer the house is cooler in the day, but warmer at night than it used to be. In winter the extra warmth at night is good, but not so good in summer.

I decided on polyester insulation, as I was concerned about the health effects of breathing in fibreglass fibres. It's a little more expensive though, and the R rating is a bit lower than fibreglass too.


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## AlterEgo (8 May 2009)

awg said:


> the heat trap issue is affected by several variables.
> 
> including, the mode of heat entry into the house, its materials, orientation and roof/ceiling/wall characteristics.
> 
> ...




I've found the same thing. I need to run the air-con at night during summer (I'm in Queensland), which wasn't as neccessary without the insulation, however the air-con gets used less in the day than it did without the insulation.


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## moXJO (8 May 2009)

awg said:


> the heat trap issue is affected by several variables.
> 
> including, the mode of heat entry into the house, its materials, orientation and roof/ceiling/wall characteristics.
> 
> ...




Yeah, unless your house has EPS cladding, which is basically 80mm thick rendered foam walls your outa luck. My parents have it on their house and it’s like living in an esky temperature is always pretty constant. 
Hot summer nights can be made worse by kitchen heat (exhaust fan in kitchen?), having doors and windows open while aircon is running and probably a lot of other stuff.

Having tiles on your roof means they could hold the heat for a lot longer than tin. Which won't help on those hot nights.
If you are building a home, its good to look at these types of issues beforehand


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## dalek (8 May 2009)

Polyester batts are more expensive and have slightly less thermal value that glass wool so you need to specify higher R values if installing polyester.
Glass wool is no longer fibreglass, hasn't been for some time.
The issue with F/glass was the solubility of fibres in the lungs, which is not a problem these days although some people can be allergic to almost anything.

The loose blow-in style product has a tendency to settle over time and should not be considered IMO. 
While most regions are adequately served by R3.5 batts if you are in a region that suffers temperature extremes, e.g. A.C.T. then R4.0 would be the choice.
Lots of windows will have significant impact on thermal performance and you need to ensure blinds / curtains are used to get best results.

While you will get positive resuts in hot weather the most noticable improvements will be in cold conditions with a comensurate reduction in heating bills.
There really is not much to debate, the cost /benefit analysis is excellent and the improved comfort is great.
Just make sure any downlights are given plenty of clearance when installing the stuff.


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## jackson8 (8 May 2009)

Julia said:


> Gary, thank you.   Why are you opposed to the polyester?




as mentioned by another it is more expensive to acheive the same R. rating also polyester is used as a sound proofing material as it is a denser material 

you would be well advised to check out the ignition point spec. for anything that you may be considering


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## Smurf1976 (8 May 2009)

Been involved with this one plenty of times...

Personally I'd go for glass wool batts as the cheapest and most effective solution. They won't settle or otherwise wear out - they should last as long as the house. It won't set the roof on fire and it doesn't make an attractive nest for pests (though rats especially will nest just about anywhere). And they're also usually the cheapest option as well.

Everything else has problems. Cellulose (blown in), wool, foam and polyester are not inherently fire proof. 

Your wool jumper might be fairly safe to wear if there's a fire, but low density batts in the roof sure aren't. Same with the shredded newspaper etc. It's fine when they do the demo with it packed as dense as they can get it. But coal or wood don't burn under those conditions either. Pack it loosely as its intended to be installed and it's an entirely different story when the blow torch is applied unless the manufactuer really has done the fire retardant treatment properly (and plenty don't).

Polyester is better than the rest, but it still doesn't have the inherent fire proofing of glass wool. I'd be a lot happier with polyester or foam than wool or shredded newspaper though, but in terms of fire safety I'd still rather have glass wool or rock wool.

Why the concern about fires? Let's see... Wiring, light fittings, heater flues, sparks under the eaves during a bushfire. Lots of ways a fire can start in the roof with or without insulation. If you're going to put something up there, then having something that won't burn makes sense to me.

Another problem with the blown in types is they move about and/or settle over time and this greatly reduces effectiveness. It can be manufactured and installed well with fire retardents and a sealing spray. Do that and there's not much to worry about and yes it will work. But I've seen plenty of situations where that isn't the case... 

As for foil, well that's in a completely different category to the rest since it's a reflector of radiant heat. It does some good, especially for keeping the heat out if installed directly under the tiles / tin when the roof is installed. But in my opinion it's not as good for keeping the heat in as the other types of insulation. It's still better than nothing, but batts will keep you warmer in winter.

Regarding the heat trap in summer issue, that's only true if the indoor temperature is above both the desired temperature and the actual outdoor temperature AND you don't have a lot of ventilation. If you ran a properly sized air-conditioner all the time (not that I'm saying you should) then it wouldn't be an issue - adding the insulation would simply alter the tmes the A/C runs and reduce its overall running hours and cost. If you had a window open and a decent airflow then there just shouldn't be a problem assuming it's not hot outside at night. And if it is hot outside, then you'd need the A/C on anyway...

I'm sitting in a house that's 8 degrees warmer than it is outside right now. I guarantee you that if I open the windows at each end then the inside temp will drop to near the outside temp in a matter of minutes. That applies regardless of the actual temperatures. But I do know about that problem in a situation with a lack of ventilation - but then most houses do have windows. 

Main thing if you want to stop the house turning into a greenhouse is to make sure it's not a greenhouse to start with. Sun shining in closed windows is going to heat the place up, adding insulation merely increases the effect. Awnings etc are the solution to that problem.

If I were you, I'd be insulating with glass wool batts. Just to make sure everything's safe though, downlights must not be covered (this is the law) no matter what sort of insulation is installed.


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## Julia (8 May 2009)

Smurf, thank you for very comprehensive comments, as always.
And thanks to everyone who has given their views.  It's very helpful.


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## moXJO (8 May 2009)

Smurf1976 said:


> Been involved with this one plenty of times...
> 
> 
> As for foil, well that's in a completely different category to the rest since it's a reflector of radiant heat. It does some good, especially for keeping the heat out if installed directly under the tiles / tin when the roof is installed. But in my opinion it's not as good for keeping the heat in as the other types of insulation. It's still better than nothing, but batts will keep you warmer in winter.
> ...




To get it under the tiles on an existing roof you more or less have to re-roof the entire house(pull old tiles off and then re-lay them). It’s a massive job and not worth the cost. Same for tin roof


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## awg (8 May 2009)

Smurf1976 said:


> Been involved with this one plenty of times...
> 
> 
> 
> ...




Very true.

I am almost passionate about passive solar design.

In the ideal circumstance, with correct axial orientation of the house on block, eave width, window placement, construction material, insulation and a simple but optimised ventilation, plus a few other cheap tricks, the need for any heating or cooling can be vastly reduced in most areas of Oz.

Its a real shame more is not made of it, its world saving stuff.

Add solar,recycling, permaculture etc and I'm sure one could halve individual energy consumption in 20yrs  

accurate in what u say about inside vs outside temps....if u have traffic noise however, we keep the windows shut at night..big dif in temp


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## Smurf1976 (9 May 2009)

moXJO said:


> To get it under the tiles on an existing roof you more or less have to re-roof the entire house(pull old tiles off and then re-lay them). It’s a massive job and not worth the cost. Same for tin roof



Agreed. It's really only an option in a new building or if the roof is replaced, but it's worthwhile if you do want to keep the heat out. 

Consider if you've got a black tin roof of, say, 150m2. The sun shining on that at mid day is equivalent to running electric 60 fan heaters running flat out which is rather a lot of heat. Go into the roof space and, well, let's just say you'd better like it hot.

Consider that a typical solar water heater only has 6m2 of panels which is tiny compared to the roof area. But that small area is more than enough to heat all the hot water the house is likely to use during sunny conditions.  

A light coloured roof will reflect much of that heat. I did an experiment on a garden shed with one area painted black, the other white. The white area was slightly warm (about 20 degrees outside and clear sky). The black area was too hot to comfortably touch.

Keeping the heat in, as opposed to out, is a somewhat different scenario since the radiated heat isn't really such an issue. By the nature of wanting to keep the heat in, there generally isn't much sun to start with. To keep the heat in, just insulate everything you can. The more the better, although above about R4 the financials won't be so good and there's a limit to how much insulation it's practical to fit in any given space.

Qld - Try and keep the heat out. Ceiling insulation will help but so will awnings, foil and anything else that keeps the sun out. If the house is like an oven during the day due to the sun shining in and you don't have air-conditioning, then that's when insulation could make things worse at night.

Tas - Just insulate the lot. In the rare event that it's actually hot at night, well there's an opportunity to run the heat pump in cooling mode (which helps clean it out by the way). And I think most would rather be hot 2 nights a year than freezing all through winter anyway.

SA - Ideally you want to keep it out in Summer and keep it in during Winter. Insulate and, during Summer, have some means of keeping the sun out (awnings, shutters etc).


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## Julia (9 May 2009)

I'm undecided about whether to go ahead with it or not, mostly because of fear of holding in the heat in summer.

House is not uncomfortably hot in summer, rarely need to use the aircon.

Would definitely like it warmer in winter.

Can anyone estimate how many degrees warmer the nights would be in Qld with insulation?

With thanks.


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## CapnBirdseye (9 May 2009)

Depends upon the construction of your house.  The roof space should be (almost definitely will be) ventilated. This will take the warm air out, from wind and through a chimney effect... Insulation will stop heat coming in too.

If you have got a pitched roof and put in just above the ceiling its not a problem.  Also if your house has lots of thermal mass - ie. made of block, brick or stone, this will help with overheating - it gets warm the heat goes to the walls and remits at night when temperatures drop.

I'm say insulation is a good investment.


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## moXJO (9 May 2009)

Might as well try it if it’s not going to cost much. You can always take them out again. Call an insulation mob to find out temperature ranges(might have to ring around)


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## gazzaw (9 May 2009)

Julia,
If you are worried about holding in heat during summer, then go with glass wool bats and also install a couple of whirlybird roof ventilators per roof cavity.
I found that the whirlybirds greatly decreased the roof temperature in summer and also help to remove moisture from bathroom exhaust fans. 

Just make sure you install them close to the highest point on the roof on the sunny/hottest side (hot air rises) and to help catch the breeze.

Now I notice the heat conduction via the brick veneer walls more than through the ceiling.


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## Dowdy (9 May 2009)

Insulation is one thing but i found the best thing to keep the heat out (for summer) is to get your windows tinted.

Trust me, i know. I've never in my life had air-con in my house. I was painful before i got my windows tinted but now it's actually quite cool. Get the mirror tint - it blocks 70% heat and 99%UV rays


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## Julia (9 May 2009)

Thanks for additional responses - much appreciated.

Re tinting windows:  can appreciate it would reduce heat in summer if windows are exposed, but actually almost no sun comes in via windows in summer because of deep eaves plus sunblinds externally.  But it does come in during winter when sun is lower in the sky and I'd hate that not to happen.


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## Smurf1976 (10 May 2009)

Julia said:


> Re tinting windows:  can appreciate it would reduce heat in summer if windows are exposed, but actually almost no sun comes in via windows in summer because of deep eaves plus sunblinds externally.  But it does come in during winter when sun is lower in the sky and I'd hate that not to happen.



It sounds like you've already got decent passive solar design with the windows. 

If that's the case then adding insulation will basically result in a stabilisation of temperatures. That is, assuming the windows are shut, no heating and no air-conditioning then the variation in inside temperature will be less than it is at present. 

Answering the "how much difference will it make?" question is a difficult one in a situation where there's little heating or cooling used. It will depend a lot on house-specific factors, but realistically I'd expect that with insulation it will be cooler during the late afternoon and evening and warmer in the morning compared to not having insulation. Less heat gained during the day and less lost at night. Obviously if you're running any heating, cooling or significant ventilation then that will affect things a lot.


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## Prospector (10 May 2009)

We have always had insulation in our roof, so I dont know what it would be like without it.  Maybe it is promoted more in SA than in Queensland?


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## Smurf1976 (10 May 2009)

A few figures from my house today. I'm in Tas so you can't directly compare actual temps with Qld but it should nonetheless give an indication of how insulation holds the heat in. 

Heating was turned off at 5:50am and I left for work at 6:20. It was 20 degrees inside at 5:50am, 8.5 degrees outside. At 6:20 it had dropped to 18.5 degrees inside, helped along by having had the extractor fan in the bathroom on. 

Came home at 2:30pm and it was 19 degrees inside. Outdoor temperature now 14.4 (maximum today 14.8 on my thermometer) and it was intermittently sunny until about 1pm then overcast. I have windows facing East, North and West.

Now, quite obviously what I've done here is basically turn the house into a greenhouse. The house warmed up by itself and remained a few degrees warmer than the outside air.

I've had the heater on (3.5kW going flat out) since 2:30 and also had the oven going for half an hour, plus a few minutes use of one burner on the cooktop. It's now 21.5 degrees inside.

So overall the temperature inside is relatively stable. Even in mid winter it's generally around 13 when I get home at 6pm on a day that might have only briefly been above 10 outside. Coldest I've ever seen it inside is 10 degrees and that was after 12 hours with no heating on a completely overcast day with a maximum outside somewhere around 7.

In summer, I have only a portable evaporative cooler that's of limited benefit. But it only gets up to 30 inside when it's been high 30's outside despite the E, N and W facing windows (I close the blinds when it's hot). But on those days it's still around 25 when I go to bed and 22 in the morning with no heating.

So, in short, insulation and thermal mass will help stabilise temperatures. I've got glass wool batts in the roof, foil in the walls, nothing under the floor but it's carpeted and enclosed under. House is a fairly typical 1990's brick veneer with tin roof.


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## Julia (10 May 2009)

Smurf, thank you very much for such detailed observations.  Much appreciated.
Is there any reason why the insulation could not  be installed everywhere except over the main bedroom?   Never want that warm.  Even in winter, the door and window is open and the fan on (cold air, warm bed).

You might be surprised to know that morning temp inside here in winter can be as low as 12, when outside falls to around 3, 4 or 5.   Previous evening heating would have brought it up to about 24.

Smurf, on an unrelated issue:  what would be the likely reason for items in frig to be getting frozen when refrigerator temp control is turned to the warmer side of adjustable range?  I have a vague memory of being told not to do this, that both frig and freezer should always be kept at medium temp control.


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## Smurf1976 (12 May 2009)

No reason why you couldn't insulate just part of the ceiling as long as whoever is installing it can work out (in the roof) where the walls are. Usally that's not too hard but in some situations it can be more difficult (though not impossible) to work it out. But if you've got the window open then it's not really going to matter a lot since the airflow through the window is a far more significant heat transfer than loss / gain through the ceiling (depending on how far the window is open, but there's a reason why it's worth sealing even small cracks in cooler climates to stop heat loss).

As for the fridge, assuming it's a two door conventional (upright) frost free  fridge / freezer:

The thermostat usually controls one motor and refrigeration system for both and is usually measuring the temperature in the fridge. There are some models where all this is reversed.

When the motor runs, cold air is blown into the freezer with a small amount directed via a duct into the fridge. A baffle in the duct, adjustable via the balance control (the other temperature knob) adjusts how much cold air goes into the fridge but it's always a relatively small amount compared to the freezer.

The thermostat is the one which, when adjusted to "off", causes the motor to stop, usually with a "click" sound like an oven thermostat. The balance control, which adjusts the baffle, is the other one. The labelling on these is often highly confusing so ignore what it says and work out for yourself which is which.

Some more expensive models have completely separate refrigeration systems for the fridge and freezer. In that case, ignore all I've said here and just adjust each thermostat to get the temperature right. Most common fridges in Australia are as I've described however.

Ideally you want about -18 in the freezer and about 4 degrees in the fridge if it's for normal use.

Set the baffle to half way and adjust the thermostat to get the right temperature in the fridge. 

If the freezer is not at the desired temperature, adjust the baffle to correct this. Turning the baffle down, so less cold air flows into the fridge, will cause the motor to run longer to maintain the same temperature (set by the thermostat) in the fridge. The effect of this is that the freezer becomes colder. Reverse if you open the baffle more.

It should be possible to get it about right following this proceedure. Adjust it once per day (no more) when the doors have not been opened for a few hours until it's right. In most cases though, setting the baffle half way and adjusting the thermostat to get the right temperature in the fridge will leave the freezer at about the right temp.

Be aware that running the freezer too cold may not be noticeable unless you've got ice cream or something similar that will become too hard if it's too cold. But at the extreme, if you turned the baffle right down so the freezer was extremely cold, you'll end up with some rather big electricity bills and will also be wearing out the motor etc unnecessarily. So it's worth a bit of messing about to get it right.

If putting a thermometer inside the fridge or freezer, put it amongst something bulky (eg a bag of frozen peas or in a glass of water) so that it reads the average temperature. The temperature of both the fridge and freezer will vary as the motor switches on and off - you want the average and not one extreme or the other that may have been reached just before you check the thermometer. 

If there's a meatkeeper, "chill zone" or any other routinely adjustable vent into the fridge then adjusting this will upset the balance just like adjusting the baffle. I'd recommend leaving them in the same position all the time (open unless you specifically want them closed for some reason) and just adjusting the baffle to get the temperatures right. Doing this won't add to your electricity bill with most fridges.

If the fridge has a butter condioner box in the door then be aware that this is literally a heating element running 24/7. Extra power to run the element and then more power to extract the heat it produces. Leave it off unless you really do want it on.

Also be aware that there will be some means that the fridge tranfers heat to the surrounding external air. This could be a condenser coil (black metal piping) at the back or underneath. Or it could be embedded in the walls of the fridge with heat transfer through the metal casing (common in newer fridges). Wherever it is, it needs air to circulate and if it's an external coil should be kept clean - failure to do so hinders the operation of the refrigeration system leading to more running, more wear and higher power consumption.

And the obvious one, the fridge should ideally not be in the sun or near any heat source. If there's no alternative, then a white fridge will suffer less from this than stainless steel or other dark colours which absorb more heat.


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## GumbyLearner (12 May 2009)

Heat rises.

Not too fussed about the ceiling, what about the floor?

http://en.wikipedia.org/wiki/Underfloor_heating


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## nunthewiser (12 May 2009)

thankyou for your posts smurf


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## GumbyLearner (12 May 2009)

nunthewiser said:


> thankyou for your posts smurf




Yes I agree. Thankyou smurf for sharing your knowledge.


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