## 1 Introduction  
Recently, building energy consumption of modern cities has increased remarkably, owing to the economic development and improvement of living standards, e.g., the energy consumption of a residential building is up to 25.2% of the total energy consumption in Hong Kong [1]. In a modern city, the energy consumed in high-rise buildings increases significantly because the number of high-rise buildings increases rapidly owing to the increasing urban population and land price [2]. Because approximately 50% of building energy consumption is caused by air conditioning [3], it is essential to reduce the consumption of refrigeration systems used in high-rise buildings for the sustainable development of a modern city. Solar cooling technology is considered a promising method to decrease the consumption of air conditioning, owing to the coincident trends of solar irradiance and cooling demand. In addition,the solar LiBr/H\({}_{2}\)O absorption chiller is thought to be highly suitable for large-scale buildings, among the available solar thermal cooling systems [4]. However, the application of a solar-absorption chiller in high-rise buildings is accompanied by financial constraints. The operational cost of solar cooling (primarily produced by the natural gas) exceeds that of traditional air conditioning [5]. Because the investment cost of solar cooling is higher than that of air conditioning, the solar/natural gas driven absorption chiller is considered infeasible for high-rise buildings. [PERSON] [6] suggested solar refrigeration aided by electric energy as an alternative for high-rise buildings. In this solution, the absorption chiller is driven by solar energy, and a vapor compression chiller is employed to provide auxiliary cooling [7]. It was demonstrated that the payback period of the abovementioned system reduced by 61.3% compared with that of a solar/natural-gas-driven absorption chiller owing to the efficient use of auxiliary electricity energy. Because the payback period of the [PERSON] solution is up to 36.2 years, we [8] proposed another system called the solar-absorption-subcooled compression hybrid cooling system (SASCHCS) as a more economical solution for high-rise buildings. The operating principle of SASCHCS is approximately similar to that of a vapor-compression chiller with dedicated mechanical subcooling [9]. The most remarkable advantage of the SASCHCS is its high performance as an absorption subsystem and the utilization of low-grade solar energy owing to the high evaporator temperature of the absorption chiller, thus resulting in the enhanced energy reduction [10]. Further, it was found that the product cost flow rate of the SASCHCS is superior to that of the Shirazi solution when they are used in high-rise buildings [11]. Compared with solar photovoltaic (PV) cooling, which is thought to be the most economical solar refrigeration technique available in recent times [12], the net present value of the SASCHCS is 50.04% greater than that of the solar PV chiller [13]. On the other hand, the exergoeconomic design principle of SASCHCS was presented to make the system more cost-effective [14]. Especially, the exergoeconomic-optimized criterion of the absorption chiller was analyzed in detail for the hybrid system used in the low-rise building, since the performance of the absorption subsystem reduces dramatically with the rise of its size [15]. Moreover, the 3E design of size in the absorption subsystem based on the annual data was carried out to make the SASCHCS work more efficiently with relatively low cost in the entire operation period [16]. The SASCHCS suffers from off-design operation frequently because of the variation in hot water conditions as well as the cooling demand of buildings. Accordingly, the off-design model of a hybrid system is highly important to solve the operational issue, i.e., the quasi-static simulation of daily operation as well as the impact of the operating strategy. A parametric model of the absorption-subcooled compression hybrid cycle was built by [PERSON] [17].