Systematic examination of energy performance gap in low-energy buildings

Low-energy buildings (LEBs) play an important role in improving energy efficiency, reducing energy use, and mitigating carbon emissions to achieve the 2050 global decarbonisation target. However, increasing evidence indicates that energy performance gap (EPG), defined as the difference between predicted and actual energy performance, significantly inhibits the successful delivery of LEBs. This study aims to systematically examine EPG in the context of LEBs using the combination of the methods of literature review and meta-analysis with 76 carefully selected cases of LEBs from previous studies. Drawing on the dialectical system theory, the study develops a novel dialectical system framework to ensure the systematicity and comprehensiveness of the examination of EPG in LEBs. A new life cycle–human–technology–organisation framework is also established to clarify the complex causes of the EPG. The findings reveal that EPG in LEBs ranges from −86 % to +483 % with an average of +58 %. More than 80 % of the LEBs have a positive gap that their actual energy consumption is greater than their predicted energy consumption. It is found that technology-related and human-related causes of EPG have been popularly investigated, but organisation-related causes have been far inadequately explored. A roadmap for pursuing zero-energy gap is proposed to promote the successful delivery of LEBs. Knowledge gaps are identified, which point future research directions for achieving a systematic understanding of EPG in LEBs, bridging the EPG, and realising LEBs effectively.