Just what is the point of bubblewrap?

I managed to get some 5ft wide cellophane a year or two ago and I have lined the OUTSIDE of my greenhouse with it.

To explain; I have a timber greenhouse (cedar) so what I did was put the cellophane up and fixed it down by screwing laths to my glazing bars. That is I trapped the cellophane between the laths & glazing bars.

The first year I did it I took the sheeting up one side,over the roof and down the other side.

Although this worked I found it a bit impracticable because 1) my auto lights wouldn't open! 2) when I wanted to remove the sheeting to allow more light in around April/May I had to remove the side coverings as well.

In subsequent years I have done the roof and walls seperately, in fact because I don't use this greenhouse much during the summer I just leave the sides covered all the year round.

In April/May when I have removed the roof covering I keep a bit of fleece at hand in the event of a 'frost' being forecast. This I fix with drawing pins to the underside of the roof.

 

The maths side isn`t too difficult, perhaps it`s just the way it comes across in text

An informed choice is far better than simply asking a salesperson to suggest a product.

If you then ask him/her to explain why it`s better than one at half the money.. that`s when you`ll get blinded by science :D

 

your still blinding them with science when in fact they require a simple answer,is thats so difficult ???

 

Hi macleaf,
When talking about the movement of heat inside, into and out of, a lossy glass box.. then the answer must be yes.

There is no simple answer due to the variables involved which all interact.

Growing plants in a greenhouse involves controlling all the variables to promote the best environment.

If you understand at least something of how those variables work and interact, it will make it easier to acheive that environment.. without breaking the bank.

Houses today are designed to be energy efficient year round, while greenhouse design and energy efficiency is still pretty much in the victorian era.

I think most gardeners try to reduce their impact on the planet, but greenhouses in general have room for improvement.

 

hex, you are getting toooo high tec. for me. I do understand science but this is too much. :D :D

 

Hi Fancy

The thread involved a technical question, to answer it you need to get a bit technical.. ultimately it`s just simple multiplication and subtraction

A simple and probably accurate answer would have been "..because everyone else uses it"
but that`s not too helpful without the "why" is it?

If nothing else, this thread does prove that there is some interest and thought going into improving greenhouse performance.

Of course it`s easier to switch on a heater..but where`s the fun in that?

 

Hex, I cannot argue with that, however in mitigation most people try to improve greenhouse performance in the best possible means that allows them to and at low cost.

 

Hi Fancy
Easily done "and" low cost is always good

I understand it`s not always feasible or possible to improve things beyond a certain point, some may be completely happy with the greenhouse as it is and that`s ok too :D

I just think with so many greenhouses out there,
it could be a missed opportunity to find some new (and maybe not so new) energy saving ideas that people are using or have used.

After reading about the "peak oil" situation, we may be needing some before too long :D

 

"Just what is the point of bubblewrap?"

The point of bubblewrap is to provide a transparent blanket which will retain heat while passing light.

There are two kinds of bubblewrap, double skinned and triple skinned. The double skinned is more readily available not only in garden centres but also in office suppliers. It only partly does the job. The triple skinned version ensures that you have two layers of polythene as a minimum all over, this provides sealed air pockets over the whole area.

Covering the greenhouse with a single skin of polythene or cling film does not do much for retaining heat, as the greenhouse is not normally sealed so there is no sealed air pocket.

Heat convection causes some unusual effects at times, it is possible, if the air pocket is too large (volume) for the air to flow up one side and down the other. We experienced this effect once with a gravity hot water system which should have hot water going up one pipe, while the cool water was coming down the other pipe. For some reason it started going up and down the same pipe.