No, to add an insulating layer of air. Believe it or not the 24 13w cfls add enough heat to make a difference.
I should've gone with the anti-condensate film, which I have on my 30x60 clearspan. That clear poly is almost dripping in the morning. Roll up the sides and its out though..
Fisher - do you eventually vent the greenhouses at night when the plants are bigger and the nights are warmer?