PNNL

Abstract

The performance-based compliance alternative available in most energy codes, intended to provide energy efficiency equivalent to that of prescriptive compliance while allowing innovation and design flexibility, can instead result in sub-standard energy performance in both the short and the long term. The potential deficiencies in modeled buildings originate with subtleties in the energy modeling rules, allowing building systems that consume more energy than their real-world, prescriptively-designed counterparts. This performance gap is exacerbated over subsequent decades as less efficient permanent features of the building remain while elements with shorter lives are regularly upgraded in most buildings. This paper summarizes an investigation into the topic for Pacific Northwest National Laboratory and the City of Seattle, including identification of the principal deficiencies exploited in the modeling path, and several potential code amendments that could resolve these deficiencies and establish better equivalency between prescriptive and performance compliance paths. The study, focusing on Seattle and Washington State energy codes, offers lessons and implications for other jurisdictions and energy codes.