It is difficult to compare cost of “basic” vs. “green” cost, as the latter implies a different architectural design, not necessarily or solely the addition of elements, each of them with a clear price tag, to the basic design. Thus, research so far calculated excess cost based on the average cost of green buildings. Building a typology from a selection of buildings can hardly be as detailed as actual building specifications, which include hundreds of items. Moreover, every building has its own characteristics, which affect the appropriate green solutions, as well as their costs and benefits. Thus, research findings are inevitably limited to specific case studies, and hard to extrapolate to other green buildings. Still, they provide some indications in a market suffering from lack of information.