Caterpillar Tunnel Ventilation
We’re at the height of summer, it seems like a good time to talk about ventilation in covered spaces.
Generally speaking, the more ventilation, the better! If you are very uncomfortable working in a a space, chances are good the plants and beneficial insects are uncomfortable and stressed, too. Room temperature (72F) is a temperature that people, plants, and insects are typically happy at.
To determine how strong your fans should be and how many you’ll need, try using a greenhouse fan calculator.
Your first step to cooling things down may be adding shade cloth. Many plants prefer diffuse light and it can make a big difference in the temperature, too. .
Ventilation in unheated/unwired tunnels can be improved if you:
install simple self-opening vents in the peaks of the end walls
add wide doors that can be left open (as opposed to the gather and tie-down method) that is typical of low tunnels and temporary caterpillar tunnels, or a single standard size door.
raise the height the sidewall plastic can be lifted. If you have hip boards installed and you’re finding the heat is overwhelming, raise the hip boards the next time you change the plastic (or earlier if you want). Heat rises, and it will accumulate and fill the tunnel from the ceiling down until the point at which it can escape. If heat is being generated faster than it can escape, you’ll find it gets too hot.
In tunnels with electrical wiring, you may want to:
add exhaust fans
pull air in from the colder side of the structure, if there is one.