The cloth type will greatly affect the use of your curtain systems.  Blackout cloths can be used to change the day length for your crop and be used as a heat retention cloth at night.  The cloths come in a range of shade percentages to best fit your individual application. The cloths can reflect the infrared light range to reduce the heat gain and diffuse the PAR light the crop uses to increase the look and health of the plant.  The right cloth can be pulled at night creating an attic space above the curtain and reducing your heat loss saving you as much as 35% annually.