A toolkit towards performance-based green retrofitting of HVAC systems

Retrofitting by technology upgrade is one of the main approaches to improve heating, ventilation, and air conditioning (HVAC) system energy efficiency and reduce greenhouse gas emissions. However, it is not unusual for HVAC retrofits to fail to achieve the expected performance level. This has given rise to the so-called “gap” between the expected and actual performance of retrofitted HVAC systems. Although green technologies have been invented in order to reduce operational energy, many designers and contractors do not have adequate technical and managerial experience to use advanced green technologies. In addition, the lack of guidelines and poor awareness of green project management commonly make the outcomes of retrofitting projects uncertain. These knowledge gaps and practical deficiencies have in the past prevented practitioners from achieving performance-based HVAC retrofits. Therefore, a systematic approach should be developed to improve the performance of retrofitted HVAC systems. This research aims to develop a toolkit that presents a systematic process to inform stakeholders in HVAC retrofitting projects. The toolkit is expected to encapsulate and analyse the relationship between key performance attributes and critical success factors which affect the HVAC retrofitting. The six main objectives of this research are: (1) to identify the key performance attributes affecting the client’s decision-making in HVAC retrofits, (2) to identify the critical success factors influencing the planning, design, construction, and operation and maintenance of retrofitted HVAC systems, (3) to identify stakeholders' perspectives on key performance attributes and critical success factors, (4) to investigate the relationships between the key performance attributes and the critical success factors, (5) to develop an analytical network process (ANP) model to assess the success of HVAC retrofits, and (6) to develop a toolkit capturing the outcomes of the above, which can be used in a green HVAC retrofit for an expected level of performance. This research adopts a quantitative approach to seek solutions to address the research questions. Based on factor analysis of a sample of 144 HVAC practitioners’ responses collected by means of a questionnaire survey, the research identifies the key performance attributes and critical success factors in HVAC retrofits. ANOVA and t-tests are employed to test whether there were statistically significant differences in the importance of the attributes and factors between different respondent groups. To explore the relationships between the attributes and the factors, multiple regression and correlation analysis are used to describe the strength and intensity of the relationships. Finally, an ANP approach is used to develop a model to examine the interrelationships among the factors, which will help stakeholders to determine the success of a HVAC retrofit. Findings from the research are categorised into four areas: (1) the identification of seven key attributes and eight critical factors of HVAC retrofits; (2) the identification of the different stakeholders’ perspectives on a green retrofit project; (3) the investigation of the relationship between attributes and factors; (4) the development of a decision-making approach for measurement of the success level in HVAC retrofits. This study contributes to new knowledge and improved understanding of HVAC retrofits in four areas: (1) the seven important attributes and eight important factors can not only help clients evaluate green HVAC retrofitting opportunities but also provide stakeholders with comprehensive information to assess the performance of retrofitted HVAC systems; (2) the different stakeholders’ perspectives on a green retrofit project can improve the stakeholders’ awareness of potential conflicts in HVAC retrofit projects, and ensure that the different expectations, agendas and interrelationships are well understood and managed; (3) the relationships between the attributes and the factors can provide valuable information for stakeholders, and in the fulfilment of the expectations of clients, stakeholders will know what they have to do is fully committed to the joint efforts; (4) the ANP technique is demonstrated to provide effective solutions and to facilitate the evaluation of the success of HVAC retrofits. This research also has significance for the industry sector. The toolkit, which comprises strategies, decision-making methods and major retrofitting activities, outlines a systemic process for stakeholders to implement the planning, design, construction, operation and maintenance of HVAC retrofitting projects.