BACKGROUND:
Extreme heat is the leading cause of weather-related mortality globally and disproportionately affects people experiencing homelessness due to prolonged outdoor exposure, limited access to cooling, water, and healthcare, and high prevalence of chronic illness and medication or substance use that can impair thermoregulation.1,2 Despite this vulnerability, people experiencing homelessness are rarely included in the design of heat-health responses.3 Co-design may allow equitable climate adaptation by embedding lived-experience expertise within intervention development.4

METHODS:
In Sydney, Australia, we established a sustained, cross-sector co-design group comprising people with lived experience of homelessness, clinicians, researchers, and local government staff. The group met regularly over two years and was supported by a co-design expert, shared governance, equitable remuneration, and administrative coordination to ensure continuity. Lived-experience members were mentored in co-design and research processes and participated in shared decision-making across intervention design, operational planning, research, and dissemination. The process was iterative, with learning from each deployment informing refinements.

RESULTS:
Co-design outcomes extended beyond the initial intervention concept. Through lived-experience leadership, the cooling hub evolved to incorporate solar-powered batteries, reclining chairs for recovery, peer-support, entertainment, and strengthened safety and security protocols. As the project matured, the group divided into operational and research streams to manage complexity while maintaining shared membership. The co-design team remained consistent, supporting deployments across 11 heatwave days between January 2024 and January 2026 in public parks. Members jointly contributed to scholarly outputs, including a published perspectives article,⁵ and conference abstracts. The project also received national and international media attention.

CONCLUSIONS:
This project demonstrates how sustained, well-resourced co-design can generate durable partnerships and adaptive public health innovation. Key enablers included cross-sector collaboration, remuneration and mentoring of lived-experience members, clear governance, and administrative support. Future research should assess feasibility, costs, risks, and comparative effectiveness of mobile cooling hubs relative to other heat adaptation strategies.