The article describes two independent projects having investors of two different types – one using public money for the benefit of community, the other was purely private money of a private economic operator. Both investors included the green and/or sustainability building objectives in their projects, and examined possible defects and deficits in thereof, also in relation to the surrounding conditions and processes. Of course, each investor discovered the concurrent development of the other investor’s plans, and determined overlapping areas of interest. In the article we describe the overlapping interest areas, variant solutions intended to lower projects costs, other pros and cons of the variants, their possible advantages and prospective degrading defects, and the harmonization of both investors’ requirements. Next to this, public opinion on the solution was determined and evaluated, with trends and biases where identifiable. Then the variant best suited to both investors was agreed upon, just with slight final modifications to better satisfy the public and both investors, and to avoid possible future induced defects.