The design of healthcare facilities is a complex and dynamic process, which can be supported by design support models. This process involves a large number of stakeholders, of whom some have specific health-related needs. Evidence-based design is an emerging approach for the design of healthcare facilities, basing design choices on scientific data. Apart from the problems accompanying the limited access to, and limited availability of, scientific evidence, the design of a building itself is characterised by dimensional, technological and stakeholder complexities that are derived from technology philosophy. This article deals with the derivation of performance indicators and design solutions for healthcare facilities and links this search to the foundations of evidence-based building. The In2Health design model is elaborated as a framework to steer this process and support architects, programmers and process managers. The applicability of the model in the evaluation and design processes of buildings is illustrated by two case studies concerning (i) the evaluation of the indoor environment for older people with dementia and (ii) the design process of the redevelopment of an existing hospital.