I'm afraid not really for this. I know of UK one for 'Rock Growing' which deals in orchids that grow outside in the UK, but that's the only other one I use.
I'm sure people would help if they could here. I think the hard thing with this post is that it is more construction related then orchid related. Lots of people know lots about orchids here. I don't know enough about buying new windows to help. I can help you with growing tips once you have everything setup. I grow mounts indoors.
I's go with triple pane windows and put all the insulation in the seat you can. Also have electric service nearby for lights, etc.
With your South/Western exposure you might want to look into windows that automatically adjust for the amount of light and close internal blinds.
Hope this helps a bit and some other folks will chime in now.
For my self, I'd put a lot of insulation in the seat, something I forgot to do.
is the window going to be connected to the house? when i grew in windows, i found that my space was limited because i had to avoid touching the glass in winter or the leaves would get cold damage so go for high insulation.
also, you may want to get some sort of tempered glass or opaque white glass because it refracts light so the light is still bright but wont burn the orchids since the other glass will let the sun right in.
the downfall if being connected to your home is that it may be hard to control the tempurature, humidity, and air movement since it directly correlates to your home. a muffin fan in the top corner of the window may suffice but misting can be a hassle if there things nearby to get ruined.
consider also, having some sort of drainage as part of your design as the water has to go somewhere and you might not want to lug your orchids to the sink every other day. if theres a catchment then it could double as a humidity tray
i live in tucson where the sun is scorching 24/7 so this may/may not help and this was at a past home. im considering putting in a new one. good luck with your project!
-omar
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