Hey everyone, i've been a lurker here for a while now but i was wondering if the combined mind of the physics forum could help me come up with a few more solutions to this problem. I'm looking into creating a low cost composite material which would absord solar energy during the day and slowly release in inwards at night for a tent like structure for a civil engineering project. So far I've looked at using laminated foil layers which are painted black ok the outside and using vacuum like pockets in various layers to slowly allow he heat through. I've also had a look at some of the new phase shift materials: http://peswiki.com/index.php/Directory:Phase_Change_Material If anyone can think of any other principles i could investigate then that would be great. Cheers for your help guys.