Appraisal of building envelope alternatives in terms of overall physical performance.

The envelope as fictional building element acts as a filter intended to regulate energy andmass flows. The overall performance of the envelope is ascertained by the combined effects ofthe functional components. Thus a methodical approach is required for the comparativeappraisal of envelope alternatives in terms of multiple perfomance requirements andidentication of the best overall performer. While some requirements pertaining to the same ordifferent physical quantities are in accordance with each other, others are mutually exclusive.One requirement may also affect any number of components. Conversely, each componentmay involve any number of requirements. Representation of each alternative is achieved bymeans of a conceptual element model. Performance indicators are applied for quantitativemeasurement of the extent to which requirements are fulfilled and are expressed as functions ofelement attributes. An application of the method is carried out on a set of generic alternatives.