A framework for building-related carbon coefficients and primary energy factors for networked electricity supplies

Abstract

This Technical Note describes a framework for handling the inherent complexities of carbon emission and primary energy factors for networked electricity supply systems within building energy codes and similar policy instruments. The proposed framework reflects the main characteristics of carbon emissions from such networked supplies, while retaining a level of complexity (and simplification) comparable to that of procedures used in existing building energy codes. The main issues that are addressed are the time-varying nature of factors for networked supply, the impact of variability and curtailment for variable and intermittent renewable sources of electricity and relationship between “marginal” factors and “average” factors. These are important issues as the currently common use of annual system-average factors can result in misleading guidance as to the most effective ways of reducing carbon emissions or primary energy demand. The note first explains the relationship between building energy performance ratings and networked electric supplies. It then discusses the characteristics of electricity demand and the networked supply systems before proposing and discussing the framework. Practical application: A framework that can improve the reliability of building energy performance rating based on carbon emissions or primary energy factors.