Summary The paper describes the Demonstration System suggested by the authors. This Demonstration System enables efficient performance of alternative life-time process planning, multicriteria assessment, utility degree determination and selection of the most efficient versions of various projects and their constituent parts: • Determination of rational design solutions for walls, windows, roof structures, basement floor, heating system. • Selection of rational constituent parts of a project (selection of construction site and location, multipurpose complex assessment of buildings, determination of rational types of contracts). • Selection of efficient interested parties (contractors, suppliers, neighbours). • Alternative designing of life-time process of a project (one-family dwelling houses; agricultural, cast-in-place, prefabricated panel, and thermal renovation of buildings), its multicriteria assessment, determination of utility degree and selection of the most efficient version: • Determination of ef...