以高雄市政府建築物立體綠化及綠屋頂補助計畫為評估對象，依據政策評估指標六面向:效能性、效率性、充分性、公平性、回應性、適當性為架構，深度訪談利害關係人，包含政策執行者、專業顧問、環保團體之政策監督者，以及使用者與受補助者。研究目的為評估政策實施品質，同時檢討政策推動的阻礙因素。研究結果顯示綠屋頂隔熱降溫效益獲得一致肯定，但減緩都市熱島效應之政策目標必須擴增綠化面積與提升植栽養護品質，長期持續實施之後才能正確評估效能。目前申請補助不踴躍，因為經濟誘因不足、宣導層面不廣。阻礙因素在於初期設置成本、後續維護費用負擔，以及人力不足。建議設計規劃階段提供專業技術輔導，包含水資源管理、防水層評估、生態美學教育，以及綠屋頂搭配光電板配置，結合開源節流策略，使綠屋頂能永續經營，有助於達成政策預期目標。

The present study aimed at conducting performance evaluation and making recommendations on the green roof subsidy policy that the Kaohsiung City Government promotes for existing buildings improvement. Analytical framework is based on the six aspects of policy evaluation indicators: effectiveness, efficiency, adequacy, equity, responsiveness, appropriateness. Stakeholder in-depth interviews on site were used to gather opinions and perceptions from policy implementers, consultant, policy supervisors of environmental protection association, as well as users and recipients. The purpose was to evaluate the quality of policy implementation and to review the impediments to policy promotion. The research results show that the effectiveness of green roof insulation and cooling has been unanimously affirmed. However, the policy goal of mitigating the urban heat island effect requires more greening and better quality of planting and maintenance which have to be implemented continuously for a long term in order to evaluate its effectiveness correctly. At the current stage, the challenges for the promotion of the green roof subsidy policy are passive applicants, insufficient incentives, and the narrow promotion of target users. The barriers of implementing green roofs for existing buildings are substantial upfront cost, maintenance costs and staff shortage. It is suggested that professional technical consultants should involve in the design planning, such as water resources management, the waterproof layer assessment, ecological aesthetics education, and the configuration of green roofs with photovoltaic panels. These integrated strategies of broadening income sources and economizing expenditure help to manage green roofs sustainably and to achieve the policy desired goals.