Solar Glass - Pilkington K and plant growing

Hi JWK. I have never heard of it until now. So I just had a Google. http://www.lifestylewindowsandconservatories.com/pilkington_glass.asp

I don't know anything specific about it, but my physics tells me that things that are poor radiators are also poor absorbers of the same radiation. So I suspect that it is a coating that reduces the amount of heat radiation that passes through the window in both directions. This would keep it cool in summer, less radiation coming in from the sun. But also warmer in winter as less heat is lost from the house by radiation. This is exactly the same way that cloud cover in winter reduces the chance of frost. The clouds prevent the radiation from the earth being lost into space, whilst when there is no cloud the heat that is radiated from the earth results in a colder frostier ground. It sounds very sensible. The only downside on the domestic front is that on a sunny day in the winter you won't get the benefit of the sun as some of its radiation will be turned back.

Your plants don't really want the heat at this time of year. They want the light, which is a different shorter wavelength. The coating on the glass obviously doesn't effect light. It it did the glass would appear darker when you looked at it. So on balance it seems to be good for plants as well as people.

 

I have a feeling it does look darker.

My windows that are fitted with it have a very subtle greenish tinge, (from the outside), not noticable until you compare it with non K glass.

Sounds like I read your link first Peter, but I swear I only read it after writing the above.:D

 

I sometimes split Double glazed units and reuse the glass for single glazing...'cos I'm parsimonious not tight:p,but I can't use the treated pane because of the dark tint on it.

 

I always trust a man of the cloth :D

I am not surprised that it is a bit darker. Its very difficult to cut out just the heat wavelengths, without effecting the light wavelengths. But I don't think that will be too much of a problem JWK. Some of my seedlings are on the shady side of the house and others on lower tiers in the greenhouse, where it is very dark. Not ideal - but they will still grow. In later months plants will be getting far more light than they can use. But I doubt that we are there now.

 

"we have plenty of office plants growing"

If its "office landscaping" (rather than folks own pots along the windowsill) they may have installing growing lights, instead of normal bulbs, above the plants?

 

I doubt that it is directional. The bit that does the work will be a thin film on the surface of the glass. It won't have a back or a front. The only reason that it is on the inside pane of a double glazing unit it to protect the film from the elements and from people cleaning the windows.

 

I did an A level project on the effects of light wavelengths on plant germination and growth (a means of converting Physics to Botany!). But I can't remember the results now ...

Similar conversion of Chemistry to Botany doing chromatography comparison of the dies in flower petals, and I presume Maths was something to do with statistical analysis of plants, but I can't even remember what the project was now! Or the Biology one for that matter ...

Anyway, I scraped through but got amazing marks in Computing (which was a subsidiary subject) because I fancied Wendy who drove the ICL 1900 mainframe computer

 

As far as I know you always get a label telling you which side should face inwards, even without a self cleaning coating.
The treated K glass should be on the inside.

 

Would you Adam & Eve it, I fell over this on my travels just now: