TABLE OF CONTENTS Prescriptive specifying (as used in traditional design-bid-build) describes individual products and the methods of construction used to put the products in place. By contrast, performance specifications concentrate on end results that are expected for entire facilities or the systems that make up those facilities.
Think of traditional prescriptive specifications as grains of sand that are compiled to make up a shoreline; performance specifications as stretches of beach. An environmental restoration project could include descriptions of the grains of sand and prescriptive details of how to place the grains in lifts to satisfy the inspection of the environmental engineer. The same environmental restoration project could be accomplished by describing the results wanted: a stretch of beach that will sustain landside grasses 200 ft from the mean low waterline, and provide seasonal recreation for local citizens. Obviously, the grains-of-sand approach is products/methods-based; the stretch-of-beach approach is end results based.
Building codes have been steadily shifting to a performance-based orientation, allowing designers and builders to devise alternative solutions to structural, fire protection, or sanitary requirements. The building code organizations recognized that traditional building requirements discouraged innovation and sometimes prevented the use of products or systems that added new safety or efficiency features to facilities. With the new performance orientation in building codes and standards, the specifications community has an incentive to update its publications and products, thereby redressing the current bias toward prescriptive specifications.
