Has any thought been given to LED 4 foot tube lights?
The customer rejected T5 because of the cost. I don't think LED is cheaper than T5.
The T8 ballasts are rated to -17 C. They might not produce any light at that temperature, but a couple can be re-fitted to LED if/when needed. Thanks for that idea.
Plastic sleeves cost about the same as lamps. I'm tempted to throw a couple in to see how they work.