Australia's Nationwide House Energy Rating Scheme: the scientific basis for the next generation of tools

Abstract

The Nationwide House Energy Rating Scheme (NatHERS) underpins the performance targets set within the Building Code of Australia, and has been instrumental in reducing the energy and greenhouse gas emission impact of Australian homes. But with the last significant upgrade of the scheme and its simulation engine more than a decade ago, NatHERS is showing its age. This paper examines the emerging evidence questioning the scope, assumptions and algorithms that define the scheme, and points to a scheme that may be becoming less accurate at assessing contemporary homes and digital lifestyles. Furthermore, the inability to integrate into typical computer aided design (CAD) processes entrenches inefficiencies within the housing design industry. Responding to this evidence the paper provides a vision for evolving the scheme and its tools to better address policy needs and ensure that it remains pertinent to both industry and government, highlighting issues of relevance to many rating schemes and energy assessment tools.