Polytunnel Ventilation

We are thinking about getting a poly tunnel, either 3 x 4.5 metres or 3 x 6 m from First Tunnels. I would like to get it right from the start and what I'm wondering is, is a vent screen kit a worthwhile investment for polytunnels this small, or would a double sliding door at the front and a single door at the back provide adequate ventilation? The tunnel is to be erected on a north/south axis and the prevailing wind comes from the west – if we were to get a side vent screen kit, would only one on the west facing side in conjunction with the doors be enough or would one be required either side, pushing the price up considerably!

Thanks for the reply - we were intending to contact First Tunnels but thought it would be better to get some unbiased advice as any company is going to want to sell more for more profit! We are in East Suffolk, about 1 mile from the coast - protected from all directions apart from the west, where our shelter belts will probably take about another five years to take effect.

 Yep, same as Rem858. Debris netting or scaffold netting over your door frames, then the plastic can just be stapled on over winter to protect from frost. You dont need to spend a fortune, on ebay you sometimes find a few offcuts for sale.

I read last night that you can just add additional hoops when you come to replacing the cover, so it's worth considering that when siting your tunnel.