Greenhouse glazing and UV filtering

[Phil Kabza]

I am beginning researching the selection of glazing for a planned greenhouse/solarium addition attached to our house. As it must meet architectural and structural engineering (hurricane) standards, it will use rigid glazing panels rather than films. At this point, the benefits of using twin-wall polycarbonate panels put them ahead of other considerations.

I find conflicting information regarding the benefit of either allowing or filtering UV. Specifically, it appears that filtering UV from the light spectrum disorients a number of winged greenhouse pests, reducing damage to plants (and reduces my use of sunscreen!). On the other side, published research finds higher levels of beneficial compounds, carotenoids, in plants receiving supplemental UV-A and UV-B light.

Polycarbonate panels use polymers that include UV inhibitors to prevent yellowing and degrading of the panels. This suggests that any supplemental lighting I install should emphasize UV-A and UV-B wavelengths.

I expect to find more information as I dig further, but wonder if any group members have covered similar ground and can make suggestions?

[Paul Trudeau]

Interesting topic, Phil.

One greenhouse aquaponics grower I know reports that his Skyphos lettuce, which is normally red, grows green in his polycarb (twinwall) glazed greenhouse.  Same seeds he grows outside grow red...

[Phil Kabza]

Paul: That is supported by the photos in this publication, showing the difference between supplementing or not supplementing UV light: http://www.ars.usda.gov/is/pr/2009/090223.htm .

[k edmonds]

Does anyone have knowledge of ETFE?  It seems hard to source or find detailed information.  What I have read is that it is very strong and allows great light penetration.

[Phil Kabza]

I love this forum! Here I am a building product researcher and I didn't think of ETFE until suggested by k edmonds. Below are a couple of links for those interested. At first glance, application of ETFE film to residential scale greeenhouses is likely to be too complicated, at least until a manufacturer integrates the material into some modular form that is easily purchased. But it has some very interesting properties, the most important being full spectrum light transmission. You lose the benefit of UV suppression as an insect control mechanism, but gain the value of UV-A and UV-B for plant growth stimulation. There's much more to be learned. Does anyone else have more complete info?

http://holscot.com/products/etfe-panels/ 

http://architecture.about.com/od/construction/g/ETFE.htm

k edmonds said:

Does anyone have knowledge of ETFE?  It seems hard to source or find detailed information.  What I have read is that it is very strong and allows great light penetration.

[Paul Braun]

Hi Phil,

Deglas Alltop Acrylic panels are available with or without UV transmittance...

 

http://greenhouse.roughbros.com/item/acrylic/tegories-glazing-acryl...

available in clear UV Transmitting and clear UV Blocking

There are lots of other links available, this is just the first one in Google.

Take care,

Paul