MR 4.1 & 4.2: Recycled Content
There are a total of three points available for this topic. You have the 4.1 which is your basic 10%, you have the 4.2 which is your more advanced 20%, but then if you hit a whopping 30%, you can apply for an additional ID credit for exemplary performance.
This whole intent of this credit is to encourage builders and designers to incorporate recycled material into their project rather than using virgin matierals. The idea behind this theory is that using recycled materials is more renewable. One thought that I have regarding this is that sometimes it may create a larger carbon footprint to recycle old materials than it would be just to go out and harvest new materials. I think that the reasoning behind wanting to recycle is mainly that it will reduce the size and strain of our landfills.
Regardless of the whole theory behind recycling, this credit section does have 3 points available, which could be pretty important in your overall LEED strategy.