This fabric is for wind prevention.
Have you noticed before that there is strong wind at a rooftop place on a tall building?
Although you want to expose yourself to cool wind, it is not so comfortable when you are hit by continuous strong wind.
In that case by putting tent fabric you can prevent wind from coming in directly!
Maruhachi Tent Corporation / （株）丸八テント商会
5-7-10 Sakae Naka-ku Nagoya Aichi Japan