I ran 1950 watts in an 8x12 foot shed which holds a 52 square foot canopy inside. Not sure if this helps. I assure you it was very warm. Way warmer then 3000 watts of air-cooled hps. Again maybe i should of dimmed the 600 watt QB's down to 450-500 watts a piece and i could of achieved better results in terms of heat. Im coming from an open perspective here trying to have open conversation in a dominant LED thread. Just trying to learn. I don't mind playing the bad guy here.
How hard were you driving each qb? If you run them really hard they will get pretty hot in a sealed environment. You could always add some more boards and run them softer depending on the drivers you have. Most people that have success with led report best results with temps around 82 degrees Fahrenheit.