Nowadays, energy retrofit for existing buildings has become a worldwide approach to reduce total energy consumption. A wide range of energy-efficient retrofit measures is actively affecting the decision process, of which retrofit alternatives should be used. The existing study aims to evaluate the effects of façade retrofit measures in residential buildings in Cairo using life-cycle cost analysis. An extensive variety of façade retrofit alternatives was explored individually and combined. A hypothetical benchmark building was used as a reference to represent typical residential buildings in Cairo. DesignBuilder was adopted to assess and quantify the energy-saving potentials for the proposed measures. The evaluation process was based on a parametric analysis of four major façade parameters that are affecting building energy performance; exterior wall configuration, glazing type, window-to-wall ratio and external shading. Thermal characteristics for façade retrofit measures were analysed to give a better understanding of the thermal performance for each retrofitting case. Results showed that the most cost-effective alternative for façade retrofit is to install a 1 m overhang as an external shading device, which reached 1.4% life-cycle cost saving and 18% energy saving. Finally, a sensitivity analysis for the main life-cycle cost supplements was presented to show major variables that are affecting life-cycle cost analysis.

如今，现有建筑的能源改造已成为降低总能耗的全球性方法。范围广泛的节能改造措施正在积极影响决策过程，其中应使用哪些改造替代方案。现有研究旨在使用生命周期成本分析评估开罗住宅建筑外墙改造措施的影响。单独和组合探索了各种各样的外墙改造替代方案。一个假设的基准建筑被用作代表开罗典型住宅建筑的参考。DesignBuilder 被用来评估和量化拟议措施的节能潜力。评估过程基于对影响建筑能源性能的四个主要立面参数的参数分析；外墙配置、玻璃类型、窗墙比和外部遮阳。分析了外墙改造措施的热特性，以便更好地了解每个改造案例的热性能。结果表明，外墙改造最具成本效益的替代方案是安装 1 m 悬挑作为外部遮阳装置，达到 1.4% 的生命周期成本节约和 18% 的节能。最后，对主要生命周期成本补充进行了敏感性分析，以显示影响生命周期成本分析的主要变量。结果表明，外墙改造最具成本效益的替代方案是安装 1 m 悬挑作为外部遮阳装置，达到 1.4% 的生命周期成本节约和 18% 的节能。最后，对主要生命周期成本补充进行了敏感性分析，以显示影响生命周期成本分析的主要变量。结果表明，外墙改造最具成本效益的替代方案是安装 1 m 悬挑作为外部遮阳装置，达到 1.4% 的生命周期成本节约和 18% 的节能。最后，对主要生命周期成本补充进行了敏感性分析，以显示影响生命周期成本分析的主要变量。