seem to have a similar problem. I had two green lots in Willow Creek's Sage Estates while playing with another family. now that I've switched to one of the lots in Sage Estates, both of the lots are neutral and the neighborhood instantly switched from very green to neutral the last time I traveled, even though I made the one I play with even more green if the build mode descriptions are to be believed. the lot has been flip-flopping between going green and going neutral before. mostly when travelling or coming back to the family.
I know getting a region into green is only half the way. But keeping it to stay green to prevent decay, what I can say, very much a full-time job, you must keep refilling fuel cells in your upgraded applicances, making sure unnecessary electric lights remain off, all plants watered, tidy house, and some of the big power consumers are the Fabricator and Recycler themselves, if you use those all day would certainly temporary bring the footprint down.
Mine work on a rollercoaster style, it's disappointing when you all hard work turns into neutral, but a good days work around the house I know I can bring it back up.
