Polytunnel ventilation

[Stu the fish]

Morning All, Whilst planning a home brew polytunnel, the thought of ventilation struck me - most polytunnels only have end to end ventilation, whilst greenhouses have side and top to bottom ventilation. Any pro's and con's anyone can see? My polytunnel will only have entrance at one end.
I propose to have low vents at one end and high ones at the other to allow maximum circulation - perish the thought it ever get too warm again in blighty!?

Appreciate your thoughts?!

[Johnboy]

Hi Stu,
You need both high level and low levels vents at both ends.
Heat gets trapped in the canopy of poly-tunnels and you joke about heat in this country but I have had a temperature of over 120C in February so you have been warned. These vents should be permanent but also have the facility to be covered to prevent them venting should the need arise.
These vents are best made of a fairly strong mesh. There is a green one that you can buy in most garden centres, but the name escapes me, which will be insect proof. If this is put into a wooden frame with a window frame hinged attached filled with polythene with a thumb toggle fastener we do admirably.
JB.

[Stu the fish]

thanks John boy - will take that on board - 120 degress in Feb - which part of Britain are you in... British Virgin Islands...LOL thanks again STF