Can you formulate an unpowered "greenhouse" to remove warmness instead of trap it? Love the sun, but it tends to kill the hell out of...

Love the sun, but it tends to kill the hell out of my fledgling plants. I be thinking of making a small hotbox lined with moistened perlite and alternating vent holes for convection. But, I'm not sure if this would in reality aid in normalizing the steam. Any suggestions other than indoor grow lamps?
Answers:    I use my greenhouse even contained by summer by using shade cloth of 50% and keeping the door open and the vent open, too. it's hot, but I still hold plants in there...I suppose a mist system and a disciple would be helpful, too. it's come in handy when trying to solidify off seedling plants... I only put the shade cloth over partially the greenhouse so I have both shade and sun available. most of the summer plants stay in the shade subdivision. only the lemon tree stays in the sun.beside that constant heat, tho, watering becomes a each day chore.
I have a large cup greenhouse that is "unpowered" during the summer. Roof ventilation during the fry of the day in precipitate summer is primary but when that is no longer enough to cool it down I'll put white latex paint within a solo back pack sprayer and spray the roof white. This keeps my greenhouse really cool. As the summer season progresses the paint begin to fade with rainfall, etc. and by the end of summer it's virtually gone newly in time for the warmth i involve to return for winter. On a smaller scale you can top ventilate by placing the holes higher than your greenhouse because heat rises and if that doesn't cool it enough place a white sheet over your greenhouse to echo the heat away. I'd have thought shade cloth would be the answer, No?