Decision-making and diffusion dynamics of photovoltaic green roof retrofits: evidence from a tripartite evolutionary game

Purpose This study investigates the diffusion of photovoltaic green roof (GR-PV) retrofits in existing buildings from the perspective of strategic interaction among government, technology suppliers and property owners. It examines how policy incentives, firm supply decisions and owner investment choices jointly affect GR-PV diffusion, and identifies the conditions under which the market can move from policy-led initiation to self-sustaining development. Design/methodology/approach A tripartite evolutionary game is constructed to model the boundedly rational choices of the three actors. Government chooses between economic and guidance-based incentives, firms choose between supplying GR-PV and conventional photovoltaic roofs, and property owners choose between GR-PV and conventional photovoltaic retrofit options. Replicator dynamics and numerical simulations are used to assess evolutionary stability and trace system trajectories under different initial and policy conditions. Findings GR-PV diffusion proceeds through initiation, development and stabilisation. Direct subsidies are most effective at the outset, differentiated incentives help align firm supply with owner demand during market development, and guidance-based policies become more suitable as the market matures. Owner willingness to invest is the main demand-side driver, while firm supply is shaped by R&D costs and policy support. Excessive incentives may delay market formation, whereas combined subsidies promote convergence more effectively than a single instrument. Originality/value The study develops a co-evolutionary framework linking public intervention, firm response and owner adoption in low-carbon building retrofits. It shows that GR-PV diffusion is shaped by dynamic feedback among multiple actors rather than isolated cost–benefit calculations, and identifies stage-specific mechanisms and threshold conditions for incentive design and market cultivation.