A Cradle-to-Grave Carbon Index (CI) for Design, Construction and Operations of Site-Specific Buildings

Abstract

During the 1970s, the Energy Utilization Index (EUI) was introduced in terms of the annual rate of energy used per unit of floor area in site-specific buildings. It indicates energy but not total resource use effectiveness of design alternatives compared to baseline values (i.e., targets). Because of increasing concerns about indoor and outdoor emissions from carbon-based products and processes, an analogous “Carbon Index” (CI) is here introduced as a cradle-tograve design tool for evaluating the performance of design alternatives in terms of carbon emitted throughout the five stages of a building’s lifespan: siting, design, construction, operations, and demolition/recycling. This CI is expressed as equivalent mass of CO2 per unit floor area (CO2e). At each stage, this CI is determined as the sum-of-products of two factors: 1) “Primary Factors” (PF), scalars that are defined and quantified by the designer; and 2) “Carbon Impact Factors” (CIF), which are standardized 2x1 matrices that characterize the PFs in terms of “embodied” CO2e emissions in the materials, assemblies, and equipment that are installed in the building, and as CO2e emissions that are released during the “operations” of the building. This design tool is posited to foster more accurate calculations of carbon emissions for design alternatives.