Originally Posted by Chronos
Your best bet is probably to figure out what specific material you want, and then look for that material specifically. Everything's a phase change material, at some temperature or another. Given that you're talking about energy savings in a room, you're probably looking for something that changes phase at room temperature, for which some sort of paraffin would probably be your best bet (I can think of several other materials that would work, but they're dangerously reactive or toxic).
There's not a lot of phase change experimentation out there for building materials, at least that I can find on a high school student level.
I was hoping to specifically find microencapsulated phase change 'gravel' or 'sand' - not sure of the exact term but it's been used as an ingredient in concrete (about 5% ) for professional experimentation with full size concrete walled rooms. This is the experiment I was thinking of http://www.ornl.gov/sci/buildings/20...DFs/35_New.pdf
Or, alternately, those microencapsulated bits are put in wall board but I can't find those online either for purchase. The idea is to build a concrete mini-room with the materials.
Yeah, parafin could work but the perameters of the experiment would need to be changed. Or maybe a sodium solution.