Do wooden greenhouses retain the heat better overnight than an aluminium one?

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Yana

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I recently purchased a wooden greenhouse/shed combo and have been monitoring the internal temperature to compare with the aluminium ones I have. Interestingly, the wooden one seems to keep the temp higher overnight than the aluminium ones. During the day it is comparable. The thing is, there are a lot more variables as the aluminium ones are not the same size as the wooden one (which is bigger and taller) and maybe the shed addition to the wooden greenhouse makes it warmer. Who knows.
Anyone else noticed this in having wooden greenhouses retain the overnight temp better or do I have a dodgy thermometer? I have swopped the thermometers round and still get higher overnight temps in the wooden greenhouse.
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mumofstig

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There is less glass in the shed/geenhouse combo, so it should stay warmer IMO.

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GrannieAnnie

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That's just what I was going to say too!  :)

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JayG

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There is less glass in the shed/geenhouse combo, so it should stay warmer IMO.

........plus the fact that the wood is much thicker than the aluminium and a much poorer conductor of heat, so will retain its own stored heat for longer and also not transfer the heat away from the interior as quickly.)
Sow your seeds, plant your plants. What's the difference? A couple of weeks or more when answering possible queries!

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mumofstig

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That's right Jay! -  should I have said more wood then, rather than less glass?  ::)  :lol:

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Yana

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Glad I wasn't just dreaming it then.
Amazing how much of a difference it makes in terms of covering seedlings / small plants up when a colder night is forecast.
NOTE TO SELF - save up for wooden greenhouse to replace aluminium ones.   ;)
BUT - there is the painting of the wood every now and again.  :(
SOLUTION - keep what I've got and be happy.   :D

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8doubles

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If your shed is anything like my shed it is full of tools etc which heat up during the day and slowly lose their heat overnight so it is not the material the G/H  is made of which make the major difference in temperatures.

Wooden structures need regular maintainance  to avoid rotting warping and generally falling apart.

Think hard before you rush out and buy a wooden G/H , you may be better off investing in some bubble wrap ! :)


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Stree

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2 factors contribute towards the different heat retention.
The ambient temperature of timber is higher than alloy which gives it a slight advantage.
The thermal conductivity of alloy is much greater than that of timber which is great for fast heating up, but equally quick at losing heat to equalise with the local environment.
The timber structure would have a much greater mass in total then an alloy profile structure so the potential thermal mass would be much slower to respond to change than the much reduced mass of the alloy structure.

Mass can have a great influence on local heat retention, that is why large containers of water are an effective anti frost measure in greenhouses, the mass attracts the energy required to equalise the temperature of the water with that of the surrounding freezing air, the only way it can do this is by releasing the heat energy content of the water into the surrounding area, thus keeping it above freezing point.
This process is slow so that by the time daylight arrives and the temperature rises the equalising has not had time to take place.
Given enough time without a further heat source such as sunlight the equalising process would eventually complete and the greenhouse would freeze over.
A very negligible factor would be the area of glass being slightly reduced with the larger framework.

Either that or the wooden greenhouse has got a stove in it that you forgot to mention.

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Yana

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If your shed is anything like my shed it is full of tools etc which heat up during the day and slowly lose their heat overnight so it is not the material the G/H  is made of which make the major difference in temperatures.

Wooden structures need regular maintainance  to avoid rotting warping and generally falling apart.

Think hard before you rush out and buy a wooden G/H , you may be better off investing in some bubble wrap ! :)

Too late 8doubles....... I've already got it.

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Growster...

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Interesting subject, Yana.

We've just demolished a much-loved cedar greenhouse, as it had passed its grow-by date, and we want something to last for the next fifty years (we're retired, or supposed to be...;0), so we've invested in a new aluminium chap.

We had our old cedar chap for sixteen years, and on the whole, I think it was cheaper to heat and insulate than an aluminium one, because the benign timber bars far outweigh (in bulk) the slim sections you get from an ali frame, and the glass seemed to attract the build-up of warnth in the timber frame.

We may consider bubble wrap next winter as well, (and shading with debris netting, which we always do anyway),but we'll need to consider the conductivity of the frame and the glass as opposed to hoping that a timber GH will be warmer, just because it is 'wood'!

Let us know how you get on, as you've started an interesting discussion!

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Yana

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2 factors contribute towards the different heat retention.
The ambient temperature of timber is higher than alloy which gives it a slight advantage.
The thermal conductivity of alloy is much greater than that of timber which is great for fast heating up, but equally quick at losing heat to equalise with the local environment.
The timber structure would have a much greater mass in total then an alloy profile structure so the potential thermal mass would be much slower to respond to change than the much reduced mass of the alloy structure.

Mass can have a great influence on local heat retention, that is why large containers of water are an effective anti frost measure in greenhouses, the mass attracts the energy required to equalise the temperature of the water with that of the surrounding freezing air, the only way it can do this is by releasing the heat energy content of the water into the surrounding area, thus keeping it above freezing point.
This process is slow so that by the time daylight arrives and the temperature rises the equalising has not had time to take place.
Given enough time without a further heat source such as sunlight the equalising process would eventually complete and the greenhouse would freeze over.
A very negligible factor would be the area of glass being slightly reduced with the larger framework.

Either that or the wooden greenhouse has got a stove in it that you forgot to mention.

I have absolutely no idea what all this means Stree but it sure sounds amazing.    :blush:

I don't have a stove but the shed bit does seem to keep the rest of the structure warmer.

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Stree

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Never mind, I enjoyed typing it for you anyway.

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8doubles

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Interesting subject, Yana.

We may consider bubble wrap next winter as well, (and shading with debris netting, which we always do anyway),but we'll need to consider the conductivity of the frame and the glass as opposed to hoping that a timber GH will be warmer, just because it is 'wood'!

Let us know how you get on, as you've started an interesting discussion!

If you bubble wrap in the summer it diffuses the sunlight so you do not need shading (not for tom`s and cuc`s anyway) and stops the temperature dropping too much on clear summer nights !

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Yana

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Silly me i forgot about bubble wrap in all my excitement.  :)

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mjw

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My wooden greenhouse has twin wall polycarbonate on 3 sides, with a back wall clad in tongue and groove wood.  It retains heat very well and is constructed from pressure treated wood to avoid need for regular maintenance.



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