Life cycle embodied greenhouse gas emissions of new residential buildings in Uganda, A case study - Material Quantities & Modelling

The population in many developing countries is growing at relatively high rates amidst a severe housing deficit. One such country is Uganda where the demand for houses is escalating. The resulting surge in the construction of houses has led to increased use of building materials, both locally produced and imported. This heightened construction activity negatively impacts the environment since the supply chains of individual building materials and entire buildings are associated with a considerable greenhouse gas emission. However, little research has been conducted to quantify the greenhouse gas emissions associated with construction of new residential houses in Uganda. The major challenge in this regard is the lack of context-specific environmental flow data associated with building materials that could be used to estimate buildings environmental impacts through life cycle assessment. This study explored the use of proxy data compiled using hybrid life cycle inventory analysis for the Australian context to estimate life cycle embodied greenhouse gas emissions associated with a new detached residential building in Uganda. The results indicate that a two-storey single-family house accounts for approximately 945 kgCO2-e/m2 of embodied greenhouse gas emissions. The findings in this study highlight several implications for policymaking in Uganda and similar contexts about the best approaches and data sources to use when considering developing tools like life cycle assessment-based benchmarks for buildings. Additionally, the findings emphasise the need to further develop low-emission local construction technologies, and biogenic and geogenic material substitutes, and to consider regulating house size to effectively reduce building-related greenhouse gas emissions.诸多发展中国家在面临严重住房短缺的同时，人口仍以相对较高的增速扩张。乌干达便是其中之一，该国住房需求正持续攀升。住房建设的激增带动了建筑材料使用量的上涨，这些材料既有本土生产的，也有进口的。此类愈发高涨的建筑活动对环境造成了负面影响，因为各类建筑材料乃至整栋建筑的供应链都伴随着可观的温室气体排放。然而，目前针对乌干达新建住宅建筑相关温室气体排放的量化研究寥寥无几。该领域的主要挑战在于，缺乏适配当地场景的建筑材料环境流数据，而这类数据可用于通过生命周期评估（Life Cycle Assessment, LCA）测算建筑的环境影响。本研究尝试采用基于澳大利亚场景的混合生命周期清单分析（hybrid life cycle inventory analysis）所编制的替代数据，来测算乌干达新建独立式住宅的生命周期隐含温室气体排放量。结果显示，一栋两层独栋住宅的隐含温室气体排放量约为945千克二氧化碳当量每平方米（kgCO₂-e/㎡）。本研究结果为乌干达及类似场景下的政策制定提供了多方面启示，包括在开发基于生命周期评估的建筑基准类工具时，应选用何种最优方法与数据源。此外，研究结果还强调，需进一步研发低排放本土建筑技术、生物源与地源材料替代品，并考虑对住宅规模进行规制，以有效降低建筑相关的温室气体排放。