Backpack-wearing commuters all share the same summer misery: the sweaty back you get by wearing your rucksack even for a short time. 
VITL is a newly designed backpack (currently being financed on Kickstarter) that aims at solving this very problem thanks to a special back-cooling system. 
Think of it as a backpack with integrated AC: a set of small “turbines” placed near the bottom of the rear shell channel fresh air through some cleverly designed crevices and down along the wearer’s back.

The result is an improved air flow that keeps you cool while avoiding sweat buildup. The VITL comes in two interchangeable sizes (18 or 28 liters) and it features breathable straps, an AC controller and a portable battery to power the fans and recharge your devices on the go. 
A 168$ backing on Kickstarter will get you a 28L VITL plus a free 18L skin for traveling  with a lighter setup.