Closing the building energy performance gap through component level analysis and stakeholder collaborations

Abstract

Despite the endorsement of green building regulations and the incorporation of energy-efficient technologies, commercial buildings often fail to achieve the desired energy conservation goals, instead consume as much as 3 times of the predicted energy consumptions, representing a significant building energy performance gap. This study aims to develop a pathway and stakeholder-engaged methodological framework to close the building energy performance gap (EPG) through an in-depth case study of a state-of-the-art green office building. The selected case study is a 14-storey office building with spaces predominantly occupied by public and private companies. The required data were collected from building design documents, energy monitoring reports, building energy simulation models, building management system, stakeholder meeting minutes and records and discussions with the building’s key stakeholders. The collected data were analyzed by using content analysis and statistical analysis methods. The results and findings demonstrated the importance of analysis and comparison of energy consumption at building service systems’ component level rather than comparing the overall energy consumption to determine the level of EPG and unfold the details. Based on the results and findings, it is discovered that even when the overall EPG was close to zero, energy consumptions were significantly higher than the predictions for some components and significantly lower for others. The identified causes of EPG include inefficient control strategies of components, human manual overriding of automatic control operations, inaccurate prediction of after-hour demand and operations, as well as inaccurate modeling of cold and hot weather conditions in winter and summer respectively. An EPG-closing framework, which brings all key energy stakeholders (environmentally sustainable design team, main contractor, facility manager, mechanical service contractor, electrical service contractor, BMS service contractor and independent commissioning agent) together to work collectively to close the EPG was proposed. It is crucial to ensure that there are 1) motivations for involvement and participation of all stakeholders, 2) consistent naming of building service components in the prediction model and BMS system, 3) regular update of prediction models and 4) seamless knowledge transfer between stakeholders to effectively implement the framework. The outcome of this research provides the practitioners with knowledge and confidence to close EPG in their projects. The methods and processes developed and applied in this study provides useful reference to future studies.