Which type of specification allows for multiple product options?

The correct answer is open specification. This type of specification is designed to provide flexibility in the selection of products or materials, enabling multiple options from different manufacturers to be considered. Open specifications outline the required performance or qualities of a product without restricting it to a single manufacturer or a specific product.

Open specifications allow architects and designers to encourage competition among suppliers and may lead to cost savings and innovative solutions, as various products can meet the outlined criteria. This approach is particularly beneficial in a construction project where the designer wants to allow for substitutions that still meet the performance or aesthetic requirements set forth.

In contrast, closed specifications limit the options to specific manufacturers and their products, effectively removing competition and potentially reducing the chances for cost-effective alternatives. Proprietary specifications refer to a specific type of closed specification that identifies a product made by a specific manufacturer, which does not allow for substitutions. Performance specifications focus on the outcome or result rather than the specific products, but they can still limit choices depending on how they are structured. Open specifications, therefore, stand out as the option providing the most flexibility in product selection.