The complexity of products is increasing as more and more functions and structures are included in them, leading to higher requirements on better understand of users' behaviour in term of using the product during the early engineering design phase. Although, industry and academia agree that human aspects are important for the success of the product, there are few methods that support the designers concerning these factors during the synthesis of the design process. The article describes a behaviour design approach (BDA) to be used by industrial engineers, designers and ergonomists for ergonomic analysis and evaluation in product or machine design. This approach has been developed for both expert and non-expert practitioners, who can integrate user behaviour and product behaviour during the design phase for improving product performance.