Managing change and knowledge is one of the key factors that contribute to a successful energy efficient retrofit project. Due to the constraints of information, time, space and working environment, a retrofit project is more complex than expected. The significance of managing changes and dependencies is that if they are poorly or inadequately managed, changes initiated and implemented during the design, construction and operations of buildings could potentially impact negatively on energy efficiency goals. Similarly, knowledge assets are often disconnected from project teams. Consequently, lack of access to the right knowledge by project teams could result in the design and retrofitting of energy efficient buildings which do not meet the owner's goals. Furthermore, there is potential for lessons to be learned during the process of managing and implementing changes. However, this kind of information is usually not properly captured, validated and stored within a knowledge management system (KMS). To do this more effectively, the change and knowledge processes need to be integrated at the points of interactions. This paper presents an approach to integrate change and knowledge management (CKM) processes. It highlights the importance of the CKM practices in energy-efficient retrofit projects, and describes how lessons learned from change events can be captured and stored as knowledge in a KMS. Furthermore, it explains how a KMS can be expanded into a change and knowledge management system (CKMS) to support the new approach. In the concluding part of the paper, the key benefits of the proposed approach are highlighted and the approach to be taken towards the practical implementation of a CKMS is outlined.