In the chart below you can easily see the effect of adding shades. We have overlayed hourly greenhouse temperature measurements from several days before and after placing dark shades in the greenhouse. The yellow measures are post-shading and the blue are pre-shading. As you can see; before putting in the shades, the temperature min and max varied between 21 degrees to almost 50 degrees. After placing the shades the min temperature is higher - ca 25 degrees, and the max temperature around 40 degrees. The shades to some extend prevents some of the warmth to excape, but also prevents the midday heat from coming in. The temperature variations in the greenhouse have substantially decreased - and the plants love it (and the nursery employees too - it is a lot more pleasant to work here now ;-).