In the context of urban regeneration, community renovation has been a vital approach for improving local living conditions and global sustainable development. Due to the financial burden and uneven regional development, China’s community renovation has gradually shifted from the government-led model to the market-oriented model. However, these projects are subject to various intra- and inter-stakeholder barriers, particularly hidden transaction costs. This study investigates the transaction costs experienced by key stakeholders, including residents, developers, governments, and architects, with a specific focus on the pre-design phase of market-oriented community renovation projects in China. Data on stakeholders’ experienced transaction costs and their origins were collected through semi-structured interviews and questionnaire surveys and were investigated using content analysis and quantitative analysis. Results show that developers bear the most categories of transaction costs. The most significant transaction costs persist in the interactions between developers and governments, including estimating benefits and costs and receiving project approval. Furthermore, negotiating costs are the primary obstructions that hinder stakeholder collaboration. By tracing the origins of these transaction costs, the study proposes measures to optimize the renovation process by reducing transaction costs.

Buildings account for 39% of global carbon emissions, making the construction sector a pivotal contributor to climate change. In ecologically fragile plateau regions, the tension between urban development and environmental sustainability poses a significant challenge. This study examines the spatiotemporal characteristics and influencing mechanisms of building carbon emissions (BCEs) in plateau cities using an empirical analysis of 13-year panel data (2010–2022) from two municipalities and six prefectures in Qinghai Province, China. By employing the eXtreme Gradient Boosting (XGBoost) model, we comprehensively assess drivers across four dimensions: socioeconomic structure, demographic and urban environmental factors, urban expansion patterns, and climatic topographic attributes. Key findings include: (1) The XGBoost model exhibits robust predictive performance (R² > 0.9, MSE < 0.1, RMSE < 0.3), validating its effectiveness for plateau urban systems. (2) Socioeconomic structure and urban expansion characteristics significantly positively influence building carbon emissions, with GDP, per capita GDP, and built-up areas being particularly influential. (3) The interaction between climate and terrain increases carbon emissions in urban buildings. (4) While socioeconomic structure is a common factor affecting BCEs across different types of plateau urban buildings, other factors, such as urban population density, the housing construction area, and the urban shape index, exhibit variability. These insights inform policy recommendations for cross-regional carbon flow balancing and adaptive low-carbon planning strategies tailored to plateau ecosystems.