I live in a semi-rural area of NJ with lots of trees, open space, and great neighbors. My wife has gotten into gardening over the past few years and learned that you can "trade" plants instead of buying them at Lowes and Home Depot. She met this old German couple on the other side of town who transformed their 1 acre property into a virtual Garden of Eden and did so by trading plants with neighbors and friends. They were preparing for the Winter and digging up some of the more temperature sensitive plants when they called my wife and asked if she wanted a few of these plants. Not wanting to pass up anything free, we drove up to their place with a few buckets to collect the tublars.
I really enjoyed their garden and their wonderful plants but what got my attention was the husband's solar heating array. This man built a 5' x 4' box with a plywood back using free scrap materials he found at various construction sites. Then he found flexible black tubing, tubing racks, and two large pieces of mirror all from job sites that were free. He placed them in the box, connected the tubing, and filled it with water.
He was shocked and surprised that the water would reach 180 F quickly and began using this hot water to heat his pool and hot tub. His pool would get so hot that he would have to shut the system down because he couldn't use all the hot water. His solar heating array (approx 20 SF) was so successful that next year he plans on building a larger and permanent one on his roof.
What impressed me about his little project was the cost, he spent no money (I'm not counting labor to build and install) on materials to build it. He just believes that "one man's garbage is another man's treasure" and kept his eye open for some good materials that people were throwing away. His motivation for this project? He didn't want to spend money (energy) on heating his pool and hot tub!
It goes to show you that you don't need to spend thousands of dollars to help the environment or reduce your energy use, you just need to be creative, frugal, and use your brains!