When did “green field’ and ‘brown field’ come into use as an economic, or investment term, and who rearranged so?

Solution 1:

The term greenfield was originally used for development projects on land that had never been built on.

In heavy industry, a greenfield project is a construction project to build a new oil well, refinery, chemical plant, etc. on a piece of land not previously used for that purpose, regardless of whether the land had been previously developed. For example, if you buy a junkyard and then build a natural gas processing plant on it, the new plant is a greenfield site even though the land was not green before you built on it.

A greenfield project is more complicated than a brownfield project, which is a project to expand capacity at an existing site: land and easements have to be sought, contracts for sale and transport of raw materials and finished product have to be negotiated from scratch, and the necessary licenses and permits are more numerous and difficult to obtain.

A related use of greenfield/brownfield occurs in the name of a US law: the "Brownfields law", signed by George W Bush in 2002, which limits liability for cleanup of "brownfield" sites for new owners. In the context of the law, a "brownfield" is a piece of land that formerly had polluting activities on it, and the land still has soil or water contamination that must be cleaned up.

If I could wager a guess, it would be as follows: the terms were first in use by business people in the heavy industry sector in a way that was only slightly metaphorical. Land at "greenfield" project sites could be truly green, but it could also be repurposed. Business people removed from heavy industry (e.g., financiers) began to use the term for its connotation of extra effort and complexity when talking about a capital project. Those factors are relevant for them even if their work doesn't involve buying land and building on it.

Solution 2:

I coined the term ‘brownfield’ in 1976, in a discussion between strategic planning teams from Strathclyde and Tyne & Wear, concerning the need to counterbalance pressures both areas faced for unsustainable greenfield development. It was first used in print by Strathclyde. This can be corroborated by Vince Goodstadt who led the Strathclyde team (and was later President of RTPI). Alan Wenban-Smith, former Structure Plan Team Leader, Tyne & Wear (1975-81)

Solution 3:

The investment terms greenfield and brownfield were no doubt borrowed from their everyday counterparts greenfield and brownfield:

greenfield, n.: denoting or located in a rural area which has not previously been built on: new factories were erected on greenfield sites

brownfield, n.: denoting or located in an urban area that has previously been built on: Hampshire has many brownfield developments

M-W lists 1962 as the first known use of greenfield, and and 1977 as the first known use of brownfield, but does not mention their provenance. They were likely just compounded from green + field and brown + field.