During the last decade, cloud computing has grown in importance, popularity and user adoption across many industries. It offers various benefits to organisations; however, many are not aware of the valuable sustainability benefits that can be experienced when using cloud computing software. This research, through case study investigation of 10 accountancy firm clients of a Norwegian cloud computing software provider, aims to identify contributing sustainability factors that affect customer decision making when choosing whether or not to purchase cloud computing services. The views of 10 established Norwegian SME accountancy firms that use the case study organisation's services were captured through face-to-face semi-structured interviewing. Results indicate that sustainability awareness is of low priority among interviewed accountancy firms and that no sustainability factors were considered when choosing to purchase cloud computing software. In future, interviewees acknowledged that sustainability factors may affect their purchasing behaviour. It is, therefore, recommended that cloud computing software providers offer real-world insights to clients on how to become more environmentally friendly by using cloud computing.