Paper Title
Life-Cycle Cost Analysis for Building Retrofitting: A Case Study

Abstract
Existing buildings account for high consumption of energy around the world. Retrofitting these buildings can significantly reduce energy consumption. Despite the existence of many strategies to improve the energy performance of existing building, the selection of the optimum one is challenging. In fact, there are many factors that affect the decision making of energy retrofitting in residential building such as budget availability, thermal comfort, visual comfort, economic benefit, and government regulations. In order to achieve the economic benefit, the life cycle cost (LCC) of the energy-retrofitting plan should be reduced. As a result, there is a need to specify the budget, thermal load, lighting load and the energy consumption level, so we can make the building retrofit project a successful one. In this paper, a case study of a residential building in Saudi Arabia was conducted to select the optimum energy retrofitting strategy. A mathematical programming model was built and used as a decision-making tool. The objective function was to minimize the life-cycle cost of by selecting the best energy retrofitting plan for more economic benefits. Also, the required thermal load and lighting load were identified and used as constraints to achieve the thermal and visual comfort requirements. Also, the budget and energy tariffs related to different consumption levels were included in the model as constraints to achieve the economic benefits. Index terms - Building Retrofitting, Binary Integer Programming, Life Cycle Cost