A time a go we received a question from James from London, he was asking if there is a tool that helps to choose / design the best sunshade.
In principle there are two possible methods right hand to be mentioned, and there are more of course, but lets explain these two. First would be the help of any 3D program that is able to show the path of the sun. The easiest would be for instance Sketch Up. If you model your solution / design and orientate your building towards the exact position of the sun, you are able to judge by the shade created, if this solution will give you enough shading. Thats of course just a beginning but already a good start. Next to that there are more sophisticated softwares solutions. The European solar shading association ES-SO has some reports and documents on their website about sunshading, and there is a program called PARASOL which is for free and helps you to calculate different solutions. Have a look here to download the program.
We hope this short answer helps to get a grip on the topic. 
facadeworld 