The fundamental goal of sustainable design for the built environment is to optimise the performance of buildings to minimise their impact on the environment. To achieve this goal, contemporary architects use a range of digital design environments, such as Computer-aided Design (CAD) or Building Information Modelling (BIM) tools. These allow architects to implement sustainable design principles and make optimal decisions about the ecological and energy properties of the building or environment being designed. Past research about architects’ uses of these tools for sustainable design have been focused on their capacity for optimising building performance and meeting architects’ design needs. In parallel, other studies have identified technological barriers and readiness factors for implementing sustainable design in several countries, including Australia. Researchers have suggested that presently, most architects are unlikely to perceive Building Performance Analysis (BPA) as their responsibility. It has also been found that the digital design tools need to more effectively support sustainable design. However, despite this body of past research, to date there is a lack of a more holistic understanding regarding architects’ perceptions about the alignment between sustainability practices and the capacity of digital design environments for supporting these, particularly in Australia. This paper addresses this knowledge gap, by presenting findings derived from semi-structured interviews with 18 professional architects in Australia, each with experiences in sustainable design and the use of digital design tools. The results are used to establish a conceptual model, which illustrates the relationships between a variety of factors affecting architects’ sustainable design practices. The findings suggest that in Australia, architects have more negative than positive experiences regarding their sustainable design practices, due to factors ranging from those related to the practice itself, to the digital design technologies and budget available for supporting their goals. This study also identifies an urgent need to enhance and better align the capabilities of digital design technologies with sustainable outcomes and associated organisational objectives, which the new model can assist in understanding and facilitating.