As we move towards net zero and place greater focus on the energy use of our buildings, it is essential to understand as accurately as possible how much energy they will actually consume in operation. The gap between predicted (modelled) and actual (measured) building energy performance can undermine the credibility of net-zero building commitments. GBCA has collaborated with the NABERS program to compare predicted performance from Green Star certified buildings with operational outcomes verified using NABERS Energy. This paper presents updated research using data from the most recently certified office buildings to quantify the building energy performance gap, providing an update to earlier research published using 2019 data. Australia is uniquely positioned to quantify this gap given the widespread adoption of both Green Star and NABERS Energy ratings. The paper also presents findings from a combination of desktop research and industry interviews to identify key drivers influencing performance outcomes, including commissioning quality, building tuning, occupant behaviour and maintenance practices. It assesses how enhanced modelling processes, verification tools such as Green Star and NABERS Energy, and policy settings including Mandatory Disclosure requirements for NABERS Energy and the Commonwealth Environmentally Sustainable Procurement Policy have contributed to reducing the gap over time. The findings support WSBE26’s focus on verification, digitalisation and performance assurance at building and portfolio scales, and provide a pathway for policy and industry frameworks to strengthen real-world performance outcomes.
This contributes to SDG 7 Affordable and Clean Energy, SDG 13 Climate Action and SDG 9 Industry, Innovation and Infrastructure.