A greyfield is previously developed land or a building that is underutilized or no longer economically viable in its current form. Greyfields are commonly commercial sites such as shopping centers and office complexes in urban or suburban areas that have become outdated due to changes in market conditions, architectural obsolescence, or lack of investment.
Greyfields differ from brownfields, which are previously developed sites that may be contaminated with hazardous substances, in that they typically do not have significant environmental, contamination and greenfields, which are undeveloped land.
The concept of greyfields has gradually evolved, particularly as the demand for urban housing continues to grow, and is now can include other urban infill opportunities, such as parking lots and even rooftops, as potential sites for redevelopment.