There is a myriad of choices that can be made when selecting and procuring building materials, regardless of the scope of the project. Rather than automatically going to the "big box" corporate retailer to buy (probably) materials manufactured in Asia with that big carbon footprint, think about taking a little time to find a Greener alternative.
The money spent at the corporate outlet leaves the local community. The transportation involved in getting the materials from outside the U.S. to your neighborhood consumes a lot of energy and produces a lot of CO2 emissions.
We are fortunate here in Sonoma County to have several local family-owned building materials retailers that are competitive in price with the corporate giants. Having grown up in a family that operated a business like that, I rarely darken the door of the "big box" store. The dollars spent in a locally-owned business circulate among friends and neighbors, rather than leaving for distant corporate headquarters.
I recently finished a kitchen facelift including new flooring. I was able to purchase American-made laminate flooring with almost all recycled content at one of the locally-owned suppliers at a very competitive price. That transaction supported American jobs, provided a healthy, low-carbon footprint improvement to the home, and circulated dollars in the local community.
This is just one small example of how thoughtful materials selection can have a ripple effect moving toward sustainability, both globally and locally.