Greenhouse Glazing - Which Type is Best?
The three main types of glazing available for greenhouses are polyfilm, polycarbonate, and tempered glass.
The polyfilm has the least amount of insulation, next is single tempered glass, and next is polycarbonate.
The chart below is an approximate of R values.
The actual value will be dependent upon the manufacturer of the material.
3mm Single Tempered Glass R Value is 1.
0 Double Tempered Glass R Value is 2.
02 6mm Twin Wall Polycarbonate R Value is 1.
587 10mm Twin Wall Polycarbonate R Value is 1.
867 16mm Triple Wall Polycarbonate R Value is 2.
439 16mm 5 Wall Polycarbonate R Value is 3.
03 Polyfilm is the most temporary of the coverings, besides being the least energy efficient.
Most polyfilms will last a maximum of 4 years, if that long.
You can save up to 40% of your energy costs by using a double layer of polyfilm with an air layer in between.
This is most often seen in commercial units rather than home greenhouses.
Many people prefer tempered glass for the aesthetic value.
They want to be able to stand at their kitchen window and look straight into the greenhouse and see their plants.
Tempered glass is still breakable, even though it is tempered.
If it is hit right by a stone while mowing for example, it may break.
But, it will crinkle into small pieces so no one will get hurt.
Some people will explore the option of double glass for their greenhouse.
You will get about 2x the R value doing this.
In most cases I have found that the cost of a double glass greenhouse is basically twice the price of a single glass greenhouse.
The last choice is polycarbonate, and of course I saved my personal choice for last.
The biggest objection to twinwall, triplewall and 5 wall polycarbonate is that you cannot see through it clearly.
I explain to people that you can see color, but not form.
Polycarbonate is a double, or more layered material.
The easiest way to visualize it is to picture looking down the end of a piece of cardboard box.
There is a sheet on the outside and a sheet on the inside with a rib that runs straight up and down between the two sheets.
This rib is what causes the distortion.
But, with the fact that the polycarbonate has the better insulation factor, plus the warranty that is typically given by the manufacturers, it is my top choice.
Many manufacturers will warrant the material against hail damage for ten years.
The typical warranty on the light transmission is that it will not vary more than 6% within ten years.
This is just a fancy way of saying that it will not yellow like products previously used would do.
GE even has a polycarbonate now with a warranty that the light transmission will not vary more than 2% in ten years.
I hope this brief overview will help you make an informed decision on which greenhouse covering is right for you.
The polyfilm has the least amount of insulation, next is single tempered glass, and next is polycarbonate.
The chart below is an approximate of R values.
The actual value will be dependent upon the manufacturer of the material.
3mm Single Tempered Glass R Value is 1.
0 Double Tempered Glass R Value is 2.
02 6mm Twin Wall Polycarbonate R Value is 1.
587 10mm Twin Wall Polycarbonate R Value is 1.
867 16mm Triple Wall Polycarbonate R Value is 2.
439 16mm 5 Wall Polycarbonate R Value is 3.
03 Polyfilm is the most temporary of the coverings, besides being the least energy efficient.
Most polyfilms will last a maximum of 4 years, if that long.
You can save up to 40% of your energy costs by using a double layer of polyfilm with an air layer in between.
This is most often seen in commercial units rather than home greenhouses.
Many people prefer tempered glass for the aesthetic value.
They want to be able to stand at their kitchen window and look straight into the greenhouse and see their plants.
Tempered glass is still breakable, even though it is tempered.
If it is hit right by a stone while mowing for example, it may break.
But, it will crinkle into small pieces so no one will get hurt.
Some people will explore the option of double glass for their greenhouse.
You will get about 2x the R value doing this.
In most cases I have found that the cost of a double glass greenhouse is basically twice the price of a single glass greenhouse.
The last choice is polycarbonate, and of course I saved my personal choice for last.
The biggest objection to twinwall, triplewall and 5 wall polycarbonate is that you cannot see through it clearly.
I explain to people that you can see color, but not form.
Polycarbonate is a double, or more layered material.
The easiest way to visualize it is to picture looking down the end of a piece of cardboard box.
There is a sheet on the outside and a sheet on the inside with a rib that runs straight up and down between the two sheets.
This rib is what causes the distortion.
But, with the fact that the polycarbonate has the better insulation factor, plus the warranty that is typically given by the manufacturers, it is my top choice.
Many manufacturers will warrant the material against hail damage for ten years.
The typical warranty on the light transmission is that it will not vary more than 6% within ten years.
This is just a fancy way of saying that it will not yellow like products previously used would do.
GE even has a polycarbonate now with a warranty that the light transmission will not vary more than 2% in ten years.
I hope this brief overview will help you make an informed decision on which greenhouse covering is right for you.
