Code refactoring is a time-consuming and effort-intensive process that is applied for making improvements to source codes. There exist several refactoring techniques to improve software quality. Some of them aim to reduce the energy consumption of the software. However, the combination of applied refactoring techniques is crucial to the success rate. In addition, to provide sustainable services on portable devices such as mobile phones and laptops, which rely on batteries, improving and optimizing the energy efficiency is important. This study focuses on examining the effect of code refactoring techniques on energy consumption. A total of 25 different source codes of applications programmed in the C# and Java languages are selected for the study, and combinations obtained from refactoring techniques are applied to these source codes. The combinations applied are analyzed using the maintainability index. Power consumption estimation tools are used to measure the energy consumption of the original and refactored codes. The results show that the combinations significantly improve the software’s energy efficiency. The results will provide a better understanding of the relationship between the energy efficiency of software and refactoring techniques. Moreover, they will help developers to improve their object-oriented code in terms of both energy efficiency and sustainability.

The concepts of sustainability and reusability have great importance in engineering education. In this context, metadata provides reusability and the effective use of Learning Objects (LOs). In addition, searching the huge LO Repository with metadata requires too much time. If the selection criteria do not exactly match the metadata values, it is not possible to find the most appropriate LO. When this situation arises, the multi‐criteria decision making (MCDM) method can meet the requirements. In this study, the SDUNESA software was developed and this software allows for the selection of a suitable LO from the repository by using an analytical hierarchy process MCDM method. This web‐based SDUNESA software is also used to store, share and select a suitable LO in the repository. To meet these features, the SDUNESA software contains Web 2.0 technologies such as AJAX, XML and SOA Web Services. The SDUNESA software was especially developed for computer engineering education. Instructors can use this software to select LOs with defined criteria. The parameters of the web‐based SDUNESA learning object selection software that use the AHP method are defined under the computer education priorities. The obtained results show that the AHP method selects the most reliable learning object that meets the criteria.