In the language of urbanism, “greenfields” usually means rural land at the metropolitan edge, where suburbia metastasizes. “Brownfields” are former industrial sites that could be redeveloped once they are cleaned of pollution. “Greyfields” — picture vast empty parking lots — refer to moribund shopping centers. Recently another such locution was coined: “redfields,” as in red ink, for underperforming, underwater and foreclosed commercial real estate.
Redfields describe a financial condition, not a development type. So brownfields and greyfields are often redfields, as are other distressed, outmoded or undesirable built places: failed office and apartment complexes, vacant retail strips and big-box stores, newly platted subdivisions that died aborning in the crash.