Here's the revised paragraph, incorporating his earlier and ongoing work in sustainability and design alongside the housing/circular economy research:

Gavin Melles's research interests centre on system dynamics modelling of complex socio-technical challenges in sustainability and the built environment, building on a longer-standing body of work on design innovation and sustainability. Earlier in his career, his research focused on design and design education for sustainability, including participatory and human-centred design approaches — an interest that continues through his affiliation with the Centre for Design Innovation and his supervision of PhD students researching the process of designing innovations across sustainability contexts. His current work applies this systems and design thinking to system dynamics modelling of Australian housing affordability, examining life-course tenure attainment across cohorts and the structural capacity constraints limiting housing supply under policies such as the National Housing Accord, alongside a broader interest in construction sector dynamics, low-carbon housing, and building performance informed by his practice as a NatHERS-accredited energy assessor. He also researches the circular economy and circular society transitions, including system dynamics modelling of membrane technology deployment and circular economy policy in Australia. A further strand of his work applies causal loop diagramming and system dynamics methods to teaching sustainable development, reflecting a sustained interest in systems thinking as both a research method and a pedagogical tool.