The Mixed Integer Programming based Multiple Objectives Optimization Model for Commercial Building Sprinkler System Layout Design

Practically, the commercial building sprinkler system is costly and accounts for nearly 1.5% of the total building cost ([1]). On the other hand, the reliability level of the sprinkler system should high enough to ensure the system performance during fire. The sprinkler layout has a significant effect both on the system reliability and the cost control. Therefore, it needs to be optimized so as to achieve the economic performance (i.e. an improved performance within a lower cost). However, most of the previous studies have just regarded the sprinkler layout as a single objective optimization (SOO) problem and the reliability level of the system is usually downgraded to minimize the system cost. One of the major drawbacks of such unreliably practice is increasing the risk of sprinkler system invalidation, then lead to huge loss from the fire. In accordance with Deb [2], a task of finding one or more optimum solutions is treated as multiple objectives optimization (MOO) when it involves more than one objective function. In reality, according to the nature of sprinkler system, most of the sprinkler layouts are MOO problems. In this study, a new MOO model is proposed for optimizing the commercial building sprinkler system layout design. It is a pioneer study that the reliability maximization is taken into account as one of the objective meanwhile achieving the other objective of minimizing the system life cycle cost (LCC). The LCC is considered to comprise the initial cost of material, installation, the annual operation and maintenance fees. The system reliability measure proposed in this study is the “individual sprinkler water spray intension”. Mixed integer programming (MIP) is employed as the optimization tool because of its own advantages over other methods in solving the facility layout problem. Finally, a case study is used to evaluate the proposed model. The results show that the system reliability level is largely improved (up to 10%) and the cost is reduced 2.03%, which fully proves the validity and practicality of the application of the proposed model in the optimization design of sprinkler layout.