Systems replaceablility ensures sustainability

Sustainability of the capital investment in a building, is in the interest of building investors and is the responsibility of building design professionals. To what extent a building investor could hold a design professional accountable if, in due course, a building proved to be not economically sustainable is not addressed in this paper. The following are addressed: the terminology used to discuss the relevant aspects of sustainability, examples of upgradeability and replaceability in man's pursuit of sustainable shelter, an initial view of the decoupling of systems required to facilitate cost effective upgradeability and replaceability of systems, a recent example of lack of sustainability, and avoidance of the need for systems replacement.