Due to global energy consumption, retrofitting has started to become more important in the urban and architectural fields. According to the International Energy Agency, most energy consumption is caused by building new structures. Retrofitting is crucial to providing sustainable and healthier interiors for the well-being of the occupants and decreasing energy consumption. Therefore, the relationship between retrofitting and user-centred design (UCD) in the design process in the sustainable design course needs significant further attention. Aim: This study aims to analyse the impact of the user profile creation phase on students’ sustainable design projects in terms of retrofitting and UCD in the early stage of the process. Method: A thematic analysis was used with a sample of 34 students’ group projects from the Sustainable Design for Interiors course at Bilkent University, Türkiye. Firstly, third-year students completed a user-profile sheet to specify their users. Afterward, students were asked to create conceptual ideas based on the user profile and retrofitting. All projects were analysed at the end of the semester. The collected project data were analysed from the perspectives of Social Retrofit, Energetic Retrofit, and Urban and Architectonic Retrofit to create a social network diagram. It indicates a relationship between themes and how much students used these themes. Findings: The findings revealed that the students are more able to integrate UCD with retrofit. Results: The results of the projects indicate that they are not separated from user and structural features. The user and structure were perceived as one factor for the retrofit design process.