There are many days when it's not so hot that with some flow-through ventilation received by using a set of screens, a driver can't shut down his truck and save fuel and engine wear. The same is true on many days when it's not so cold that a driver can't use his bunk warmer and stay comfortably warm without idling his truck.
A set of Breezeway truck window screens offer more security and keep out bugs compared to just keeping your vent windows open. An Electro Warmth 12-volt bunk warmer keeps you warm and comfortable while you sleep, rather than heating the entire sleeper/cab. Endless Breeze Fans offer a 12-volt plug with cord and three speed settings, with low am draw (under 3 amps).
More info: www.breezewayscreens.com, www.electrowarmth.com/fleet.php